In the mid-Preclassical (800 BC), several villages developed in this place and slowly evolved and grew, becoming cities and eventually major civic-ceremonial urban centers in the late-preclassical period (ca.

Copilco's decline began early in the 1st century BCE, with the increasing rise of Teotihuacán as an important cultural and religious center.

By 400 CE, the Xitle volcano near the Ajusc erupted, burying and destroying what still remained of Cuicuilco and Copilco as important ceremonial centers.

It had an incipient agriculture with an economy based on maize, hunting and fishing[2] and the inhabitants supplemented their diet with amphibians, insects and mammals from the nearby forest.

Gamio made three tunnels under the lava, finding a cultural sequence and bone remains from three individuals, containing offerings consisting of pottery, vessels, clay figurines, and Metates.

Several tunnels have been made, finding places with corpses occupying their original location, surrounded by funerary offerings items, such as ceramic ware.

According to chronicler Fernando de Alva Cortés Ixtlilxochitl (1568–1648), this was a Chichimec group, that settled in 1012 CE in the western region of the Texcoco Lake.

In his time the mexitin appeared, who requested permission to found their second capital on the islet of Lake Texcoco; it was originally named Cuauhmixtitlan in 1274.

The Chichimec (Dog lineage or Arc warriors), was a culture which controlled priests, by putting pressure on social nobility which was almost always military and oppressive.

These were nomadic groups nourished from hunting, then learned to eat cooked meat and maize; cultivated beans, corn, pumpkin, nopales, oilseeds, among other things.

[2] Manuel Gamio recounts the following: "... in the month of August 1917..." the staff proceeded to make a methodical recognition all quarries being exploited... realizing that where more items were available, was at Copilco, bordering “Colonia del Carmen in San Ángel ".