Rethinkingdisaster-inducedcollapse
in the demise of the Andean highland
states: Wariand Tiwanaku
PatrickRyanWilliams
Abstract
The role ofdroughtin thecollapse oftheancientstatesoftheAndean Middle Horizonhas received
a greatdeal of attentionin recentyears.The onlyAndean valleywherebothprincipalstatesof this
timeperiod,Wariand Tiwanaku,had establishedsettlements
is in Moquegua, Peru.Based on a GIS
networkanalysisof ancientirrigationsystemsand detailedpalaeoclimaticdata, I assess the assertionthata centuries-long
droughtcaused the collapse of statecolonies in thisvalleycircaAD 1000.
I conclude thatthe onset of the droughtsignificantly
postdatedcollapse and suggestthatfactions
of Tiwanakusocial groupswho allied themselveswithWarisettlersupsettheecologicalbalance of
water use in the valley priorto the end of the firstmillenniumAD. The increase in agricultural
caused by the fissioningof
activityin the upper sierrain conjunctionwiththe politicalinstability
forthe Tiwanaku
Tiwanaku politicalpower in the valleycreatedan environment
of vulnerability
statecolonies.It was thecomplexinteractionofsocial and ecologicalfactorsthatled to thecollapse
of thelargestwesterncolonyof theTiwanakustate.The Wariimperialcolonyplayeda pivotalrole
in thiscollapse byestablishingan administrative
centerin theuppervalleythatdrewawayresources
fromtheTiwanakustatebelow. Ironically,thepoliticalinstability
caused by theTiwanakucolonial
collapse mayhave been instrumental
in the downfallof theWaricolonyas well.
Keywords
Irrigation agriculture; drought; Peru; landscape ecology; GIS network analysis; Wari;
Tiwanaku.
Introduction
The relationshipbetween disaster-inducedsociopoliticalcollapse and social evolution
has a long historyin archaeology.In the Andes, one of the majorworldregionsin which
thepristinestatedeveloped,environmental
explanationshave dominatedthe discussion
of state collapse and long-termsocial evolutionin recentyears. The Andean Middle
Horizon (c. AD 600-1000) providesan excellentopportunity
to assess models of disaster
and collapse. The inceptionof the Middle Horizon has been linked to a long drought
1)
i
Routledge
Taylor&FracisGraup
(C
WorldArchaeology Vol. 33(3): 361-374 AncientEcodisasters
2002 Taylor& FrancisLtd ISSN 0043-8243print/1470-1375
online
DOI: 10.1080/00438240120107422
This content downloaded from 129.252.86.83 on Fri, 14 Mar 2014 00:37:59 AM
All use subject to JSTOR Terms and Conditions
362 PatrickRyanWilliams
fromAD 562 to 594 (Shimada et al. 1991) and Moseley (1992) arguesthatthe expansion
of the empireof Wari was tied to its successfuleconomic adaptationto this drought.
Kolata and colleagues (Ortloffand Kolata 1993) maintainthatthe collapse ofTiwanaku
in the Bolivian altiplano,the othergreathighlandstate,was caused by a centuries-long
droughtbeginningaround AD 1100. Many of the catastrophicexplanationstherefore
involvethe two predominantMiddle Horizon highlandcultures,Wariand Tiwanaku.
betweenthese two politieswas in the Moquegua Valleyof
The onlycommonfrontier
southernPeru (Fig. 1). Here theyestablishedimperialcolonieswithinsightof each other
thatcoexistedforsome 400 years.This small valleyis thereforethe ideal place to view
I evalubetweenthemand assess theirriseand collapse.In thefollowing,
theinteractions
ate the impactof droughton social interactionsbetween them,and on theireventual
was theeconomicmainstayin thedry,ruggedsouth-central
collapse.Irrigationagriculture
reflectthe economic
Andean sierra,and I argue thatchangesin irrigationinfrastructure
impactsof watershortages.
Tiwanakucolonizationin theseventhcenturyAD
The midvalleyzone (1000-1500 metersabove sea level) of the Moquegua valley was
intenselypopulatedin the FormativePeriod,immediatelypriorto the Middle Horizon.
There was however littlesociopoliticalintegrationand no settlementhierarchy;the
on the low foothillsnextto the
inhabitantsfarmedthevalleyfloodplainfromsettlements
rivers(Goldstein2000).
At the beginningof the Middle Horizon,c. AD 600, the firstTiwanaku colonies were
establishedin Moquegua. Representedby TiwanakuIV styleceramics,theyrepresenta
majorchangein thepoliticalcontrolof the valley.The site of Omo (Fig. 1) is a principal
GoldsteincharacterizestheinitialTiwanakuoccupationin
focusofTiwanakusettlement.
the Omo phase as an intrusiveimperialcolony.Importedceramicsin utilitariancontexts
suggestthatthe populationwas ethnicallyTiwanaku,not local people subjugatedby the
altiplano polity.House formsresemble those of the altiplano,not the local cultural
traditions(Goldstein1989).
In the Tiwanaku heartland,the natureof Tiwanaku controlhas been documentedat
form,
thesiteofLukurmatabyBermann(1993). A specialpurposedomesticarchitectural
withan
probablydesignedforstorage,appears in the seventhcenturyAD contemporary
increasein Tiwanakuprestigeitems.This could denotecoercedproductionforexport.At
Omo duringthe initialTiwanaku phase, individualhousingcomplexesare organizedin
Goldstein(1989) suggests
plaza communitiesthatdo not containany storagestructures.
and thatthe lack of
thatthisindicatesthepresenceof a supra-householdstoragefacility,
craftspecializationindicatesthat the primarypurpose of the colony was agricultural
productionforexport- especiallyformaize whichcould not be grownin the Tiwanaku
heartland.Kolata (1994) argues thatat Tiwanaku fromc. AD 500, agriculturalsystems
wereconstructed
usingstatecontroloflocal elites.Whiletheselocal elitesmayhave been
fairlyautonomous,theywere constrainedand motivatedby the needs and demandsof
reconstructions
suggestthattheagricultural
thestateelitein thecapital.These convergent
coloniesof Moquegua providedthestatewithexoticstapleproductsnotobtainablein the
This content downloaded from 129.252.86.83 on Fri, 14 Mar 2014 00:37:59 AM
All use subject to JSTOR Terms and Conditions
collapse 363
disaster-induced
Rethinking
3000
N
4000
....
3500
N~~~~~~~~~~~~~~~~~~~~~~~
-
-50
p500:at1
+
20 kilometers
yt%-
ft
Baul
2000,*Cerr6
~~~~1 2000
4
S
~I
g
2500 3000 3500
henChen
*Omo
2000
.1500
1000
500
49
~~~~~Ecuador
I
\
Iif0H
1000
Peru5
B~~~~~~~~~~~~~~~~~ra
'\iracochapampa
Honco Pamia
El Algodonal
Huari
Pikillacta
0
y
Pacific
Ocean
CerroBaul
500
PacificOcean
Tiwanaku
contourlinesinmeters
above sea level
Figure1 Location of the Wari-Tiwanakuinteractionin the Moquegua Valley,Peru.
altiplanoheartland.The statehad a vested interestin the continuanceof productionof
theMoquegua colony,althoughday-to-daydecisionsweremostlikelyleftto thecolonists.
Regardingvulnerabilityto disaster,some factorsmighthave hinderedan effective
responseby the Omo colony.The colonistswere highlydependenton extra-localpower
This content downloaded from 129.252.86.83 on Fri, 14 Mar 2014 00:37:59 AM
All use subject to JSTOR Terms and Conditions
364 PatrickRyan Williams
structures
predicatedon wealthobjectsfromtheTiwanakuheartland.Statusdifferentiation at Omo is distinguishedby preferentialaccess to itemssuch as importedredware
ceramicsand warp face polychromestripedtextiles(Goldstein 1989). The large-scale
presenceof thesebulkystatusgoods suggestsa well-developedcaravansystem- a form
ofcommunication
network(ibid.). Yet thiswas designedto move goods,notinformation.
CommunicationbetweenMoquegua and thealtiplanoheartlandwouldhave takenabout
a week,whichwould prohibiteffective
disasterresponsegiventhe degreeof interdependence betweencenterand periphery.
- the hydraulic
In additionto these social factors,the Omo economic infrastructure
organizationof agriculture- is also prone to collapse whenfacedwithwatershortage.I
It was focusedon middlevalley floodplain
now examine thateconomic infrastructure.
farming.There was no greatinvestmentin extensiveterracesystemslike those of the
upper portionof the valley,nor do the canals cross extremelysteep and ruggedterrain
forgreatdistances.The technologicalaspects of irrigationare not verycomplex.Given
the very differenthydrologicalregimes of the altiplano and the western valleys,
Tiwanaku hydraulictechnologieswould not be applicable to the environmentof the
Omo colony.
The Omo agrarianenvironment
could cope withminortectonicactivity.Adjustingto
changesin surficial
topographydoes notrequiregreatamountsofhumanlabor.Likewise,
while extremefloodeventscould destroycanal intakesand inundatefields,recoveryof
fromthissort of event could be accomplishedrather
the Omo agrarianinfrastructure
losses mightbe intense,butwould be limitedto months,
quickly.Short-term
productivity
ratherthanyears.
vulnerableto drought.
valleybottomsystemswereparticularly
However,thelow-lying
Upvalleyagrariansystems,evaporationand seepage willall diminishthe available water.
When rainfalldecreases and upvalleyfieldsneverthelesscontinueto produce at predroughtlevels,lowervalleyfieldswill sufferthe entireeffectsof watershortages.Since
the Omo fieldsare closerto the lowerend of the hydraulicsystem,theyare moreprone
area relyon mechanto watershortages.Modernfarmersin mostoftheOmo agricultural
water for their fields
ical pumpingfromsubterraneanaquifers to provide sufficient
(Moquegua Ministryof Agriculture1983) - a technologynot available to the prehistoric
inhabitants.
to certainnatural
to crisisand technologicalvulnerability
Thus,bothsocialvulnerability
hazards would have plagued the Omo colonistsof Moquegua. As discussedabove, this
wouldbe especiallypronouncedshouldupstreamagricultural
systemsbegin
vulnerability
to use morewaterat a timewhen highlandrainfallwas decreasing.This is exactlywhat
happenedin the seventhcenturyAD, withthe intrusionof theWaricolony.
The riseof theWaricolonyin theseventhand eighthcenturiesAD
The Wariexpansionled to theintroduction
of a new agricultural
technologyof profound
in thehighsierra.Although
importanceto manypartsof theAndes: terracedagriculture
terraceswere utilized centuriesearlier in the Early Horizon, as evidenced at Chavin
(Burger1992),in manyregionsof thePeruvianAndes,especiallythedesertsouth,it was
This content downloaded from 129.252.86.83 on Fri, 14 Mar 2014 00:37:59 AM
All use subject to JSTOR Terms and Conditions
Rethinking
disaster-induced
collapse 365
Wari's expansionwhichfirstopened the highsierrato agriculture.In Moquegua, there
was littleor no occupationof the highsierrauntiltheWariintrusion(Owen 1994).
The WariexpansionaroundAD 600 occurredafterthirty
yearsof 20-30 per centbelow
normalprecipitation(Shimada et al. 1991). High sierrafarmingradicallyimprovedthe
efficient
use of waterby decreasingthe amountof waterlost to evaporationand seepage
in transportfromthe rainfallareas. In Moquegua, I estimatethatthe Wari canals could
irrigate2.5 timesthe area per volume irrigatedby the Tiwanaku systems,due to their
closer proximityto the highlandrains above 3500 masl and the use of stone masonry
terracing.That is, Wari agriculturewas more thantwiceas efficient
in the use of water.
Since therewas littlepre-Warioccupationofthehighsierra(Owen 1994),Wariwas apparently not tryingto incorporatea local population; rather,the Wari settlementin
Moquegua was a colony,designedperhapsforpoliticalor defensivepurposes,but witha
strongagriculturalfoundationto supportthe colonial infrastructure.
The Wari occupationof Moquegua was centeredon the Torata valley,one of the high
sierratributariesof the Moquegua River. Recent fieldworkin the area has documented
six architectural
sitesand a canal systemconnectingthemall (Moseley et al. 1991a; Owen
1994;Williams1997). The Warisettlementis centeredat CerroBauil,an impressivemesa
withsheer sided cliffs.Excavationsindicatethatthiscolonial capitalwas an administrative/ceremonial
site witha relativelylong occupation (Fig. 2). Calibrated radiocarbon
datesfromthesitespan theperiodAD 620-1120,placingCerroBauil'soccupationcontemporarywiththe entireTiwanaku occupationof the middlevalley(Williams2001). Excavationson CerroBaul have revealedTiwanakuand Wari-Tiwanakuhybridceramicforms,
Year AD (calibrated2 sigma)
~
4
0
Wani
(Cerro BaaI)
Tiwanaku
TChenChen
El Algodonal
Algodol
Omo)
Omo)
Z
Figure2 ComparisonofWariand Tiwanaku
calibrated radiocarbon dates from
indicates 95 per cent
Moquegua.
Shading
confidencerange
of occupationbased
on all
dates foreach group.(AfterGoldstein1989;
Moseley et al. 1991; Owen 1993; Williams
2001.)
This content downloaded from 129.252.86.83 on Fri, 14 Mar 2014 00:37:59 AM
All use subject to JSTOR Terms and Conditions
366 PatrickRyanWilliams
suggestingsome interactionbetweenthe two polities(Moseley et al. 1991a; Williamset
al. 2000).
The otherWarisitesare on the 13 km Waricanal upstreamand downstreamof Cerro
site
suggestinga possible administrative
differentiated,
Bauil.They are all architecturally
terrace
hierarchy(Nash 1996). Associatedwiththecanal are severalremnantagricultural
do not appear to reflect
groups,whichare highlyeroded in some areas and superficially
However,thereare severallines of evidencesuggesting
the workof a centralauthority.
workswere muchmoreextensivethantheynow appear.
thatWariagricultural
First,these scatteredagriculturalworkscould not have supportedthe populationsof
the Waricolony.The ratiosof settlementhabitationarea to cultivationarea forseveral
contemporary'subsistence'economies in the Moquegua sierrasupportthis argument.
These rangefrom1:600to 1:1000,withan averageof 1:750.The CerroBautlcolony,being
partof an expansivestate,shouldhave had needs at least as greatas these,yetthe ratio
ofWarihabitationareas to thescatteredterraceremnantsis only1:100.This suggeststhat
theremusthave been at least six timesas muchirrigableland as theremnanttracesindicate (Williams1997).
Second, a hydraulicanalysisof the principalWari canal supportsthishypothesis.A
trenchexcavatedthroughthiscanal at the site of El Paso indicatesthatthe canal had a
maximumdischargeof 400 litersper second at thispoint.A canal of thissize could irrigate an area in excessof65 hectares(Williams1997). The terraceremnantsbelow El Paso
measureonly25 hectares,and so the area actuallyirrigatedwas probablymuchgreater
thancan be seen on the surfacetoday.
Finally,it is probable thatsome of the moderncanals in the Torata Valleywere originallybuiltbyWari,especiallythoseon theriver'ssouth-eastbanks.One ofthemainWari
sites,CerroPetroglifois locatedwithin200 metersof a modernToratavalleycanal (Nash
1996). I thereforesuggestthatWari land use includedall modernirrigatedlands in the
and theterraceremnantsassociatedwiththeWaricanal. Thisis problowerToratadistrict
ably a conservativeyetaccurateestimateof the actual land use in Waritimes.
lowerdownthevalleyis debated.
The impactofthisWariintrusionon Omo settlements
One hypothesisholdsthattheWariintrusiondroveTiwanakufromthevalley(Goldstein
But anotherhypothesisargues fora
1989), suggestinga violentmilitaryconfrontation.
stresscaused by Wari
declinein Tiwanaku agriculturein Moquegua due to productivity
in the upperdrainage.
hydraulicinvestment
land use during
This hypothesisis testedbyanalysingwateravailabilityand agricultural
the establishedWari occupationafter640 AD, when therewas a decade-longdrought
(Shimada et al. 1991). Wariagriinvolvingan average25 percentdecreaseinprecipitation
culturalfieldswould need a minimumof 25 millioncubic metersof annual dischargeto
fields,whichrepresents10 percentofthewaterneeded to irrigate
supporttheirirrigation
Omo fields.Thus, the openingof the highsierrato agricultureby the Wari empirein
conjunctionwiththe decade-longdroughtwould have reduced the water available to
production
Omo fieldsby over35 per cent.This would have decimatedOmo agricultural
in the middlevalley.
is a conquest by hydraulicsuperiThe Wari investmentin agriculturalinfrastructure
ority,accomplishedthrougheconomicratherthan militarymeans.The hydraulicmodel
providesa plausible,even convincinginsightinto relationsbetweenthe Tiwanaku and
This content downloaded from 129.252.86.83 on Fri, 14 Mar 2014 00:37:59 AM
All use subject to JSTOR Terms and Conditions
Rethinking
disaster-induced
collapse 367
Warigroupsin the valley.It suggestsan escalatingconflictover waterrightstowardsthe
end of the seventhcenturyas waterscarcitybecame morepronounced.
Two disastersthus converged: a drought-induceddecline in productivityand the
usurpationof waterrightsby a powerfulintruder.They mayhave affectedthe natureof
Tiwanaku Omo controlin the region. Centralizeddecision makingby, and economic
to thefailureoftraditional
dependenceon,theTiwanakucore area mayhave contributed
authorityto legitimizeeffectiveresponseto the disaster.The psychologicalimpactof a
competingempireestablishingitselfon a highlydefensibleand rituallychargedmountain
peak, co-optinglocal sources of water and spiritualpower,may also have constrained
effectiveresponse. The impact of the convergentdisasters drasticallyaltered the
Moqueguan politicaland economiclandscape. The politicaland economicpower focus
shiftedfromthe middle to the upper valley duringthe early eighthcenturyAD. Later
effectsofthetenserelationsare evidentin thereorganization
ofprovincialadministration
in the succeedingTiwanakuphase.
The maturecoloniesof theninthcenturyAD
Late Middle Horizon Tiwanakusettlementis characterizedby a politico-religious
center
at Omo, and a demographic-economic
centerat Chen Chen (Fig. 1). In termsof adaptive
responseto the Wariintrusion,
the politico-religious
centerattemptedto solidifycontrol
ofthevalleythroughideologicalmeans,alongwiththeestablishment
ofmorepopulation
centersand investmentin agrarianinfrastructure.
At Omo, provincialadministrators
constructeda ceremonialcomplexbased on theAkapana templeat Tiwanaku.It mirrored
the three-tieredplatformof altiplano temple centers,and is the only such complex
constructedoutsidetheTiticacaBasin (Goldstein1993). The symbolicsignificance
relates
to theforward-facing
deityon theGatewayoftheSun,arguablythemostimportant
figure
in the Tiwanaku pantheon.This figurestandsupon a three-tiered
platformflankedby
side-profile
attendants(Goldstein1993); we can thusarguethatthethree-tiered
platform
was a portrayalof power structures,
relatinghumansto gods and reinforcing
the social
hierarchyas an extensionof the earthlyand supernaturalworldorder.
This incorporationof Moquegua as an administeredprovinceduringthe TiwanakuV
period may be a reflectionof a largerreorganizationof the Tiwanaku state at thistime
(Browman 1981). This may have involvedregionalcentralizationof administration
to
Tiwanaku itself,reflectedby a declinein the domesticand ritualcomplexat Lukurmata
and a corresponding
increasein centralizedcontrolofproductionand ritualat thecapital
(Bermann 1993). This is also evidentin changesin settlementhierarchyand agricultural
productionin the TiwanakuValleyregionat thistime(Albarracin-Jordan
and Mathews
1990).
The establishment
of Omo as a provincialadministrative
centeris in starkcontrastto
thiscentralizing
process.It maypartiallybe explainedbyitsdistancefromthecapitaland
theneed to incorporateMoqueguan inhabitantsmoredirectlyintotheritualsofthestate.
The evidence seems to indicatethe developmentof a hierarchywithinMoquegua and
perhapsless centralizedcontrolof the Moquegua householdby the stateadministrators
in thealtiplano.However,investigations
at Omo's Chen Chen stylesiteof M1O arguefor
This content downloaded from 129.252.86.83 on Fri, 14 Mar 2014 00:37:59 AM
All use subject to JSTOR Terms and Conditions
368 PatrickRyanWilliams
the integrationof householdsinto the state economy,withregardto both staples and
wealthitems(see D'Altroy and Earle 1985). The frequencyof redwareceramics,most
likelyimportedfromthe altiplano,surpassedthefinewarefrequenciesfromearlierphase
excavations(Goldstein 1989). Both finelycraftedand coarse utilitariantextileswere
in the altiplanomayhave been
recoveredfromOmo M10, and theirlikelymanufacture
ofMoquegua intothestateeconomy.Staplessuch
to theintegration
even moreimportant
as llama and chuio, a freeze-driedpotato whichcan be produced onlyin the cold altiplano, were foundin domesticcontexts(Goldstein 1989), indicatingthat such staples
movedbetweenTiwanakuand herprovincialdaughter.
The strongestevidenceforstapleinterdependencebetweencore and peripheryis that
whichindicatesmaize productionforexport.New varietiesof maize witha largercob
were introduced,suggestingselectionforincreasedproduction.The manytaclla (stone
hoes) and batanes (groundstone implementsused in mass producingmaize) foundin
domesticcontextsat Omo M10 also indicateagriculturegeared towardsurplusproduction (Goldstein 1989). Recent evidence fromChen Chen compellinglysuggeststhat
massive storage facilitieswere constructedat this time (Bandy et al. 1996). Surplus
productionfor extra-localexchange,the expansion of the agrarianlandscape and the
in the
all argueforstateinvestment
increasein associatedChen Chen Phase settlements
formaize productionand export.The developgearedspecifically
agrarianinfrastructure
mentof a site size hierarchyalso arguesforincorporationof the valleyas an integrated
economicprovinceof theTiwanakustateat thistime(McAndrews1995).
This increase in sites occurredthroughoutthe middle valley,but the greatestpopulation focus and agrarianinvestmentwas in the upper portionof the middlevalley at
so the area is importantforthe
Chen Chen. Here the rivervalleynarrowssignificantly,
controlof water. This upvalley movementof agriculturallands constructedfor state
productionwas adaptive in mitigatingthe effectsof water availabilityon agricultural
production.
Meanwhile,theWaricolonyin thehighsierracontinuedto thrive.The increasein rainfallin the eighthand ninthcenturiesAD providedenoughwater,so droughtswould not
have curtailedTiwanaku agrarianexpansiondespite the Wari success. In fact,thereis
some evidencethatWariand Tiwanakuinteractionhad become moreextensive,suggestingrelationsmayeven have been amicable (Williamset al. 2000).
took place at the
I have elsewhere argued that a major institutionalrestructuring
colonial capital Cerro Bauilin the late ninthcenturyAD (Williams2001). This does not
appear to resultfroma naturalcatastrophe,but probablyrepresentsa reorganizationof
each between
theWaricolonialpresence.Severallargeplaza complexeswereconstructed,
was at its largestaround
500 and 1000 square meters.Earlier monumentalarchitecture
theassociatedbuildingscontainno evidencefordomes100 square meters.Furthermore,
tic activities,such as food preparationand consumption,householdcraftproductionor
is thatthese are buildingsin whichthe colonial goversleepingareas. My interpretation
officesand receptionhalls,butwere not residential.This
norsmaintainedadministrative
transformedthe nature of interactionsbetween elite governors,their
reconstruction
subjectsand outsidegroups.
may be a reactionto the consolidationof Tiwanaku settlementsin
This restructuring
in thisdynamicsocial environment,
few
decades earlier.Nevertheless,
a
middle
the
valley
This content downloaded from 129.252.86.83 on Fri, 14 Mar 2014 00:37:59 AM
All use subject to JSTOR Terms and Conditions
Rethinking
disaster-induced
collapse 369
thestatusquo was neverpreservedforlong,and thereis ampleevidenceforrapidchanges
in the latterstagesof the tenthcenturyAD, despitethe factthatrainfallremainedabove
normal,and would not decrease forat least another100 years.
and collapse in thetenthcenturyAD
Tiwanakufactionalization
The collapse of theTiwanakustatehas been attributedto a numberof causes. Especially
in provincialareas such as Moquegua, none of these mechanismsis well understood.
Kolata (1994) arguesfora pan-Andeandroughtin the eleventhcenturyAD. Othershave
arguedforan independentcollapse of theTiwanakuadministrative
The siteof
hierarchy.
Chen Chen is an ideal location in whichto studyagriculturaldevelopmentduringthe
terminalTiwanakuperiod (850-1050 AD). An hydraulicanalysisof thissite providesthe
data to testthesehypotheses.
Chen Chen is located at the upper limitsof imperialpresencein the region.It is the
largestTiwanaku V occupationof the area. A set of irrigationcanals,whichdrewwater
fromthe Tumilaca River,are well preserved,as are the associatedfields,and individual
irrigationfurrowsare visible on the surface. Furthermore,Chen Chen is a single
componentsitewithradiocarbondates fallingsolelyin the Late Tiwanakuperiod.
There was an upslope shiftin theprincipalirrigationcanal throughtime,and a precipitous decline in irrigatedareas and canal capacity at the end of the period (Fig. 3).
Mapping and reconnaissance indicate the existence of three principalcanals. Their
temporal sequence from lower to higher is based on the followingsuperposition
evidence. The lowest canal lies below several cemeteryand domesticsectors,and is
crossed by feedersand furrowsfromthe middle canal. This securelydates the lowest
canal's abandonmentto beforethemaximumexpansionofmiddlecanal agricultureand
well beforethe abandonmentof the site. The middlecanal also lies below some cemeteryand domesticsectors,and is crossed by a feederfromthe upper canal. Tombs lie
directlyin the course of both these canals, showingcanal abandonmentbefore cemeteryconstruction.Superpositionevidencealso indicatesthatthemiddlecanal was abandoned well beforethe site was abandoned, and fell out of use beforethe upper canal.
The upper canal is the onlyone compatiblewithall cemeteriesand domesticsectorsat
the site. It is thereforethe only canal that could have broughtwater to the site in its
terminalphases. The superpositionof the upper canal over the middlecanal also indicates thatthiswas the last functioning
canal at the site.
Given thiscanal sequence,maximumcultivationareas undereach canal systemcan be
mapped (Fig. 3). As is evidentfromthe maps,therewas a precipitousdeclinein cultivationarea from93 to 70 to 15 hectares.Excavationsoftheprincipalcanalsconfirm
this:estimateddischargecapacitiesof thesuccessivecanals declinedfrom81.5 to 63.5 to 58.1 liters
per second.The irrigation
authoritiesat Chen Chen were clearlyrestructuring
the agrarian landscapein a dynamicmanner.This restructuring
could be due to a declineof water
resources,pressuresforcingincreased agrarianproduction,political manipulationsof
agrarianinfrastructure,
or a combinationof these.Whatevertheimpetus,theresultwas a
decline in productionand the abandonmentof the settlement.At the same time,the
administrative
networksofstatedominationoftheregioncollapsed(Bermannet al. 1989).
This content downloaded from 129.252.86.83 on Fri, 14 Mar 2014 00:37:59 AM
All use subject to JSTOR Terms and Conditions
370 PatrickRyanWilliams
systemsnear Chen Chen,AD 800-1000,showingthethreesuccesFigure3 Evolutionofagricultural
retraction(oldest at top). Shadingindicatesfieldareas. (Williams1997)
sive phases of agricultural
This content downloaded from 129.252.86.83 on Fri, 14 Mar 2014 00:37:59 AM
All use subject to JSTOR Terms and Conditions
Rethinking
disaster-induced
collapse 371
Probably at this time,Chen Chen was also sacked and destroyed.Several possible
sourceshave been advanced,likelycandidatesbeing a Wariintrusionor a revoltby the
local populationagainststaterule(Moseley et al. 1991a). Littleevidenceexistsfora direct
overthrowofTiwanakuby Wari- no implementsof war or otherevidenceof directWari
conquesthas been recoveredfromextensiveexcavationsat Tiwanakusitesin the valley.
This leaves the revoltof the local inhabitantsas themostplausibleexplanation.
Earlyin theLate Middle HorizonPeriod (c. 850-950AD), droughtdid notplaythesame
role as in the earlierTiwanaku-Waritensionsof the seventhcenturyAD. In fact,thelong
droughtof thefirsthalfof thesecond millenniumAD did notsignificantly
affectthewater
supplyuntilthe twelfthcenturyAD. The average wateravailable duringthe main Chen
Chen occupation (850-950 AD) was 245 millioncubic metersof annual discharge.The
rangein decadal averageswas 225 to 265 millioncubicmeters,witha standarddeviation
of decadal averages of 12. This indicatesthatthe period was characterizedby low variationin rainfalland normalto wet conditionswhencomparedto the 1500-yearaverage.
The Chen Chen fieldsystemsneeded an estimated250 millioncubic metersto sustain
productionin all fields,whichis withinthe rangeof availabilityduringthisperiod.In the
succeedingcentury(AD 950-1050),waterstatisticsare verysimilar,witha periodaverage
of 240 millioncubic litersof annual discharge;decadal average rangedfrom220 to 260
millioncubicliters,and thestandarddeviationfortheperiodwas 13. There was thuslittle
changethroughouttheperiod AD 850-1050.
A naturalchangein hydraulicconditionscannotthereforeaccountforthe Chen Chen
collapse priorto AD 1050. However, a crucialfactoris thatthe fullcomponentof Wari
fieldsupstreamofChen Chen wouldhave required50 millioncubicmetersofwaterannually.Ifwatershortagecontributed
to thedeclineofChen Chen,itwouldhave been a result
of developmentof theuppervalleyby Wariand theirTiwanakuassociates,theTumilaca
(Williamsand Nash 2002). It is thereforearguedherethatcontrolofwaterresources,and
controlof productionand distribution
of agrariangoods, were the impetusforan independence movementby the Tumilaca at AD 950. A revolutionary
movementwithinthe
provincecould be manifestedin thedestructionof sitesthatexemplify
statecontrol.The
lack offoreignmaterialson thesesitessuggeststhatthelootingwas probablyundertaken
by membersof the same society.
Culturalcontinuity
betweenChen Chen and Tumilaca suggestslinksto the Tiwanaku
heritage,but the absence of the GatewayGod motif,conspicuouslypresentin Tiwanaku
IV and V iconography,
may suggesta rejectionof statecontrolifthisfigureis emblematic of the state (Goldstein 1989). In addition,the largeTumilaca/Chiribaya
canal in the
coastal valleywas most likelyconstructedbeforeAD 1000 (Satterleeet al. 2000; Owen
1993). In orderforwaterto reach thiscanal on a year-roundbasis,the irrigatedlands at
Chen Chen would have had to have been abandoned, because these fieldswould have
used practicallyall thewateravailable at thattime.
Conclusions
The analysisof ecological effectsof droughtin the Titicaca heartlanddoes not seem to
indicatesevere watershortagesuntilthe end of the eleventhcenturyAD (Kolata 1994).
This content downloaded from 129.252.86.83 on Fri, 14 Mar 2014 00:37:59 AM
All use subject to JSTOR Terms and Conditions
372 PatrickRyanWilliams
The hydraulicanalysisof Moquegua agriculturepresentedhere also rulesout a disaster
induced watershortages.Instead,it seems more likelythat
caused by environmentally
Tiwanaku populationswere developing,perhapsin
Moquegua
the
within
factions
local
responseto the highdegree of economicinterdependenceforcedon themby the state.
itbegan to followitsown
Once theMoquegua revolutionhad gainedenoughmomentum,
of losing one of its primemaize-producingregionsmay have
course; the ramifications
furtherdestabilizedthe authoritystructureof the state in the heartlanditself,but this
hypothesisrequirestestingat Tiwanakuitself.
The Waricolonyat Cerro Baul also appears to have been abandoned in the eleventh
centuryAD. Whilehydraulicanalysesof Warifieldsystemsdo not indicatethe hydraulic
thelateTiwanakufieldsystemsin Moquegua,theabanthatcharacterized
mismanagement
donmentofCerroBautland theprobablecollapseoftheWaristateat thistime(see Williams
2001on revisingthedate ofthisevent)are likelymorethancoincidence.The eventsprecipitatingthe local Tiwanakucollapse inevitablyaffectedthe politicsof Waricontrolin the
drainage.PerhapswiththedemiseofTiwanakustatepresence,theprincipalreasonforthe
- was
Warioccupationof Moquegua - to containand interactwiththeTiwanakufrontier
no longeran issue. Ongoingresearchat Cerro Bautlwillcertainlyilluminatetheseissues.
Nevertheless,the end of the Middle Horizon dominionby the two principalstatesis an
extremelycomplexsocial process.In Moquegua, water and social dynamicsverylikely
of directinteraction,
playeda crucialrole in the abandonmentof theonlyknownfrontier
to certainnaturaland politicalstressesa primalfactor.The ramifiwithsocialvulnerability
in the
cations of losing an importantcolony may have increased social susceptibility
forth.
brought
later
drought
that
the
stress
Tiwanakuheartlandto severeresource
The competingagriculturaldynamicsof the Middle Horizon influencedthe development of the landscape of Moquegua over the next millennium.Post-collapsesocieties
droughtthatgave the competitiveedge to thosewho
were embroiledin a centuries-long
elaborated Wari's highsierraagrariantechnology.Developed to its penultimateby the
and sixteenthcenturiesAD, highelevationterracedagriculInca empirein the fifteenth
ture is still a traditionalmainstayin the Andean sierra today. Thus, the response to
competingpoliticalforcesand ecologicalconditionshas drasticallyalteredthe ecological
dynamicsof thewesternAndean watershedsup to thepresentday.
The magnitudeof a naturalhazard cannotbe equated withthemagnitudeof itssocial
impact.Collapse and survivalare social processes,affectedby but not drivenby their
The explanatoryfocuson disasteragents,ratherthantheprocessofcoping
environments.
in social systems,has reducedthe explanawithdisasterand the inherentvulnerabilities
social elementsinto the equatorystrengthof archaeologicalmodels. By incorporating
tion,we arriveat much more powerfulexplanatorydevices thatdo not depict human
prescribedcollapses,butas activeagentsin
societiesas therecipientsof environmentally
reconowndevelopment.Environmental
in
their
and
the
environment
of
theconstruction
models,
importantrole in archaeological
structionswill continueto play an increasingly
data in orderto
and archaeologymustcontinueto utilizebothsocial and environmental
impactsof ecodisasterson the landscapeshumansinhabit.
understandthe long-term
The Field MuseumofNaturalHistory,
DepartmentofAnthropology,
1400 S. Lake ShoreDr., Chicago,IL 60605,USA
This content downloaded from 129.252.86.83 on Fri, 14 Mar 2014 00:37:59 AM
All use subject to JSTOR Terms and Conditions
Rethinking
disaster-induced
collapse 373
References
J.and Mathews,J.1990.Asentamientos
Albarracin-Jordan,
Prehispanicosdel Vallede Tiwanaku1.
La Paz, Bolivia: ProduccionesCima.
Bandy,M., Cohen,A., Goldstein,P., Cardona,A. and Oquiche, A. 1996.The Tiwanakuoccupation
ofChen Chen (Ml): preliminary
reporton the1995salvageexcavations.Paper presentedat the61st
Annual Meetingof the SocietyforAmericanArchaeology,New Orleans,LA.
Bermann,M. 1993. Continuityand changein householdlifeat Lukurmata.In DomesticArchitecture,Ethnicity,
and Complementarity
in theSouth-Central
Andes (ed. M. S. Aldenderfer).Iowa City:
Universityof Iowa Press,pp. 114-52.
Bermann,M., Goldstein,P., Stanish,C. and Watanabe,L. 1989.The collapse oftheTiwanakuState:
a viewfromtheOsmore Drainage. In Ecology,Settlement,
and Historyin theOsmoreDrainage (eds
C. Stanish,D. Rice and P. R. Scarr). Oxford:BritishArchaeologicalReports,InternationalSeries
545.
Browman,D. 1981.New lighton Andean Tiwanaku.AmericanScientist,
69: 408-19.
Burger,R. 1992. Chavinand theOriginsofAndean Civilization.New York:Thames & Hudson.
D'Altroy,T. and Earle, T. 1985. Staple finance,wealthfinance,and storagein the Inka political
economy.CurrentAnthropology,
26: 187-206.
Goldstein,P. 1989. Omo, a Tiwanaku provincialcenter in Moquegua, Peru. PhD dissertation,
Universityof Chicago.
Goldstein,P. 1993. Tiwanaku templesand state expansion:a Tiwanaku sunken-courttemplein
Moquegua, Peru. Latin AmericanAntiquity,
4(1): 22-47.
Goldstein,P. 2000. Exotic goods and everydaychiefs:long-distanceexchange and indigenous
sociopoliticaldevelopmentin the southcentralAndes. LatinAmericanAntiquity,
11(4): 335-61.
Kolata, A. 1994. The TiwanakuPortraitof an Andean Civilization.Cambridge:Blackwell.
McAndrews,T. 1995.Tiwanakucore and peripheryregions:a settlementpatternapproach.Paper
presentedat the 60thAnnual Meetingof the SocietyforAmericanArchaeology,Minneapolis.
Moquegua Ministryof AgricultureIX AgrarianRegion 1983. Diagnostico del Distritode Riego
Moquegua y Sector de Riego Carumas. Lima: Ministeriode Agricultura,Convenio Direccion
General de Aguas Suelo e Irrigaciones,ProgramaSectorialAgropecuario.
Moseley,M. 1992. The Incas and theirAncestors.New York: Thames & Hudson.
Moseley,M., Feldman,R., Goldstein,P. and Watanabe,L. 1991. Colonies and conquest:Tiwanaku
and Wariin Moquegua. In WariAdministrative
Structure:
Prehistoric
and MonumentalArchitecture
and StateGovernment(eds W. Isbell and G. McEwan). Washington,
DC: DumbartonOaks.
Nash, D. 1996. Cerro Petroglifo:settlementpatternand social organizationof a residentialWari
MA thesis,Universityof Florida.
community.
Ortloff,C. and Kolata, A. 1993. Climateand collapse: agro-ecologicalperspectiveson the drought
of the TiwanakuState.JournalofArchaeologicalScience,20: 195-221.
Owen, B. 1993.A model of multiethnicity:
statecollapse,competition,and social complexityfrom
Tiwanakuto Chiribayain the Osmore Valley,Peru. PhD dissertation,
University
of California,Los
Angeles.
Owen, B. 1994. Were Wariand Tiwanakuin conflict,
competition,or complementary
coexistence?
Surveyevidence fromthe Upper Osmore drainage,Peru. Paper presentedat the 59th Annual
Meetingof the SocietyforAmericanArchaeology,Anaheim.
Satterlee,D., Moseley,M. N. and Keefer,D. 2000.The MirafloresEl Niflodisaster:convergentcatastrophesand prehistoricagrarianchangein southernPeru.Andean Past,6: 95-116.
This content downloaded from 129.252.86.83 on Fri, 14 Mar 2014 00:37:59 AM
All use subject to JSTOR Terms and Conditions
374 PatrickRyanWilliams
Shimada,I., Schaaf,C., Thompson,L. and Mosley-Thompson,
E. 1991.Culturalimpactsof severe
droughtsin the prehistoricAndes: applicationof a 1,500-yearice core precipitationrecord.World
Archaeology,22(3): 247-71.
Williams,P. R. 1997. The role of disasterin the evolutionof agricultureand the developmentof
social complexityin the southcentralAndean sierra.PhD dissertation,
Universityof Florida.
Williams,P. R. 2001. Cerro Bafil: aWari administrative
centeron the Tiwanaku frontier.Latin
AmericanAntiquity,
12(1): 67-83.
Williams,P. R., Moseley,M. and Nash,D. J.2000.EmpiresoftheAndes: a majesticfrontier
outpost
chose cooperationover war.DiscoveringArchaeology,8: 68-73.
Williams,P. R. and Nash, D. 2002. Imperialinteractionin the Andes: Wariand Tiwanakuat Cerro
Batil. In Andean Archaeology(eds W. Isbell and H. Silverman).New York:Plenum.
This content downloaded from 129.252.86.83 on Fri, 14 Mar 2014 00:37:59 AM
All use subject to JSTOR Terms and Conditions