What we call Chichén Itzá  surely had another name when it was founded. The name means “Mouth of the Well of the Itzá” but the Itzá, an illiterate and semi-nomadic group of uncertain origin, didn’t arrive here until the 12th century.
Before the Itzá, the area was controlled—or at least greatly influenced—by Toltec migrants who arrived from central Mexico around A.D. 1000. Most of Chichén’s most notable structures, including its famous four-sided pyramid , and images like the reclining chac-mool, bear a striking resemblance to structures and images found at Tula, the ancient Toltec capital, in the present state of Hidalgo.
Before the Toltecs, the area was populated by Maya, evidenced by the Puuc- and Chenes-style design of the earliest structures here, such as the Nunnery and Casa Colorada .
The three major influences—Maya, Toltec, and Itzá—are indisputable, but the exact chronology and circumstances of those groups’ interaction (or lack thereof) is one of the most hotly contested issues in Maya archaeology.
Part of the difficulty in understanding Chichén Itzá  more fully is that its occupants created very few stelae, and left few Long Count dates on their monuments. In this way Chichén Itzá is very different from virtually every other ancient city in the Yucatán.
It’s ironic, actually, that Chichén Itzá is the most widely recognized “Maya” ruin considering it was so deeply influenced by non-Maya cultures, and its history and architecture are so atypical of the region.
Chichén Itzá ’s influence ebbed and flowed over its many centuries of existence and occupation. It first peaked in the mid-9th century, or Late Classic period, when it eclipsed Cobá  as the dominant power in the region. The effects of a widespread collapse of Maya cities to the south (like Calakmul , Tikal , and Palenque ) reached Chichén Itza in the late 900’s.
The city rose again under Toltec and later Itzá influence, but went into its final decline after an internal dispute led to the rise of Mayapán , which would come to control much of the Yucatán peninsula. Chichén Itzá  was all but abandoned by the early 1200s, though it remained an important pilgrimage site long after the arrival of the Spanish.