32 CHAPTER 1 ANCIENT AMERICA
vanced practices of irrigation, terracing, and fertil-
ization among conquered peoples of more primitive
culture. Terracing was widely used to extend the
arable area and to prevent injury to fi elds and set-
tlements in the narrow Andean valleys from runoff
from the steep slopes during the rainy season. Ir-
rigation ditches—sometimes mere trenches, some-
times elaborate stone channels—conducted water
to the fi elds and pastures where it was needed.
Agricultural implements were few and simple.
They consisted chiefl y of a foot plow for breaking
up the ground and digging holes for planting and
a hoe with a bronze blade for general cultivation.
As previously noted, the potato and quinoa were
staple crops in the higher valleys; maize was the
principal crop at lower altitudes; and a wide va-
riety of plants, including cotton, coca, and beans,
were cultivated in the lower and hotter valleys. A
major function of the Inca state was to regulate the
exchange of the products of these multiple environ-
ments, primarily through the collection of tribute
and its redistribution to various groups in Inca so-
ciety. The Inca state also promoted self-suffi ciency
by allowing members of a given community to ex-
ploit the resources of different levels of the Andean
“vertical” economy.
The basic unit of Inca social organization
was the ayllu, a kinship group whose members
claimed descent from a common ancestor and
married within the group. The joining of two
people in marriage linked the kin of each partner,
who were “henceforth expected to behave toward
one another as brothers and sisters.” Not only
brothers and sisters born of the same parents, but
fi rst, second, and third cousins (that is, all who
could trace their ancestry back to the same great-
grandfather) regarded one another as brothers
and sisters, so marriage created a large, extended
kinship group. The members of this group were ex-
pected to aid one another in tasks beyond the ca-
pacity of a single household.
A village community typically consisted of
several ayllu, who each owned certain lands that
were assigned in lots to the heads of families. Each
family head had the right to use and pass on the
land to his descendants but not to sell or otherwise
dispose of it. Villagers frequently practiced mu-Cuzco
PucaraChavinArequipa TiahuanacoNazcaIcaPachacamacChanchanCajamarca0 500 Mi.0 250 500 Km.
250Sicuani
La PazTucumanLimaQuitoSantiagoOrinocoR.NegroR.AmazonR.Sa
lad
oR
.Magd
alena
Cauc R.aR.PACIFIC OCEANCaribbean SeaARAWAKTUCANOARAWAKTUPITUPI ARAUCANIAN1463
1471
1493
1525
Boundary of Inca
Empire in 1532
Inca towns
Modern towns
Indigenous peoplesSOUTH
AMERICAArea of
main mapGrowth of the Inca Empire, 1460–1532
highland Peru. But along with their political and
religious institutions, the Incas introduced the ad-