Encyclopedia of the Incas

Inca culture was best described by the early Spanish chroniclers who were able
to consult the pre-Spanish memories of local experts from Cuzco, the capital of
the Inca Empire. Although they provided essential information for reconstructing
the Inca calendar system, they limited themselves to reporting a yearly calendar
of months similar to the Western calendar. Detailed studies, however, have
shown that the Incas developed different ways to register solar, lunar, and stellar
movements and their calendrical applications. Most importantly, the Incas
integrated the calendar with their social, political, and ritual systems, as well as
with seasonal changes, weather observations, and practices in agriculture,
irrigation, herding, and stone quarrying. There have also been studies of Inca
quipus, demonstrating the incorporation of calendar counts in the knotted-cord
records.
Of central importance in shaping the Inca calendar were a number of
astronomical observations (see Astronomy). These included: sunrise during the
December solstice; sunset during the June solstice; the sunrises of the two
passages of the sun through the zenith at noon; and the two sunsets of the anti-
zenith passages of the sun (in the opposite direction from the zenith sunrise
point). Inca astronomers were also concerned with observing the yearly
movements of the Pleiades constellation, which they termed the “mother” of all
the stars. In addition to watching this constellation for weather predictions, they
observed the constellation from its heliacal rising at dawn in early June through
its heliacal setting at dusk in early April. This pair of observations stood behind
the 328-day count of what will be described below as the ceque calendar. The
Incas also observed the Southern Cross and adjacent stars for calendrical
purposes.
Politically, Cuzco was divided into four parts. In descending hierarchical order,
the four sectors were known as: Chinchaysuyu (I) to the northwest, Collasuyu
(II) to the southeast, Antisuyu (III) to the northeast, and Cuntisuyu (IV) to the
southwest. Suyus I and III belonged to the upper, northern (hanan) half of Cuzco
and the empire; suyus II and IV belonged to the lower, southern (hurin) half. The
ceque system, which was organized within the four suyus, can be said to have
constituted the framework for the ritual calendar in Cuzco. Within each suyu,
there were nine ceques, or imaginary alignments of sacred places (huacas),
organized in three groups of three (1 a b c – 2 a b c – 3 a b c). The sets of nine
ceques were ranked in descending hierarchical order, from west to east. In
quadrant IV, however, the ceques in two groups were subdivided into six ceques
while the last two ceques were counted as one. Thus the four suyus had a total of