Most archaeologists agree that the first major settlement at Chichén Itzá, during the late Classic period, was pure Maya. In about the 9th century the city was largely abandoned, for reasons unknown. It was resettled around the late 10th century, and Mayanists believe that shortly thereafter it was invaded by the Toltecs, who had migrated from their central highlands capital of Tula, north of Mexico City. Toltec culture was fused with that of the Maya, incorporating the Toltec cult of Quetzalcóatl (Kukulcán, in Maya). Throughout the city, you will see images of both Chac, the Maya rain god, and Quetzalcóatl, the plumed serpent.
The substantial fusion of highland central Mexican and Puuc architectural styles makes Chichén unique among the Yucatán Peninsula’s ruins. The fabulous El Castillo and the Plataforma de Venus are outstanding architectural works, built during the height of Toltec cultural input.
The warlike Toltecs contributed more than their architectural skills to the Maya. They elevated human sacrifice to a near obsession, and there are numerous carvings of the bloody ritual in Chichén demonstrating this. After a Maya leader moved his political capital to Mayapán, while keeping Chichén as his religious capital, Chichén Itzá fell into decline. Why it was subsequently abandoned in the 14th century is a mystery, but the once-great city remained the site of Maya pilgrimages for many years.