Paquimé (Casas Grandes) at its height

People began to gather in small settlements in the broad, fertile valley of the Casas Grandes River after about 1130. Charles Di Peso, who excavated Paquimé in the mid-20th century, dated its heyday to about 1060–1340. A reanalysis of its tree-ring samples by Jeffrey Dean and John Ravesloot (1993) moved the chronology later: they dated the beginning of the Medio period of the Casas Grandes culture to 1200–1250 and the beginning of its Paquimé phase to about 1300. The Medio period is now placed at about 1200–1450, and, as UNESCO puts it, the town reached its apogee in the 14th and 15th centuries.

At its height Paquimé had some 2,000 adobe rooms in blocks of several storeys, with T-shaped doorways like those of Pueblo buildings, a water system of channels, reservoirs and drains, I-shaped ballcourts of the Mesoamerican type, stone-faced platform mounds and effigy mounds; estimates of its population range from about 2,500 to 3,500, with perhaps 10,000 people in the area it controlled. Its craftsmen made copper bells and ornaments, shell beads and pottery with a white or reddish surface painted in red, black and other colours, traded as far as present-day New Mexico and Arizona; rows of pens show that scarlet macaws, first brought from Mesoamerica, were bred there for their sacred feathers.

Who built Paquimé is debated. Di Peso saw it as a trading post established by Mesoamerican merchants; Stephen Lekson has linked it, controversially, with the ruling elites of Chaco Canyon and Aztec Ruins, which lie on almost the same meridian; the view more widely accepted traces its origins to the Mogollon culture, with customs borrowed from Mesoamerica. The town was abandoned around 1450 — by some estimates as early as the beginning of the 15th century — for reasons that remain unclear. When the Spaniard Francisco de Ibarra reached it in the 1560s, it had long been abandoned by its builders, and only nomadic Suma lived in the area; the nomads told him that a war with the Opata had driven its people away. The archaeological zone was inscribed on the UNESCO World Heritage List in 1998.