Although the original inhabitants of Teotihuacan left no written records, giving rise to the Aztec belief that the city was once home to other-worldly creatures, archeologists have since deduced that the area was inhabited from around 600 BC before being destroyed around 750 AD.

The Patlachique phase, (600 BC- 1 AD), runs from the time of the first settlers and saw the construction of the Sun and Moon pyramids and the Calzada de los Muertos. The Tzacualli, Miccaotli and Tlamimilolpa phases are when those mysterious gods/aliens/pre-Aztecs really came into their own with more detailed artistry and spreading influence.

The city reached a high in authority and power during the Xolalpan phase (450-650 AD), with tons of new buildings and evidence of influence in far flung empires in modern day Honduras and Guatemala. The Metepec phase signaled a decline in power before Teohtihuacan was destroyed and abandoned in the late 700s. Historians are unsure whether this was due to marauding tribes from the north (the Toltecs have been bandied about as a possible usurper) or for ecological reasons, namely the raping of the surrounding countryside to build the city and subsequent soil erosion and barrenness of the land. By the time the Aztecs arrived the site was already a mysterious collection of ruins and they subsequently turned it into a place of worship.