Teotihuacan fell in the eighth century for reasons yet unknown, but left an enduring mark in central Mexico. Three hundred years afterward the rising Toltec styled themselves its heirs. They, too, built an empire, which fell amid internal dissension in about 1200 A.D. The collapse of the Toltec created an opening in the warm, fertile basin. Into it moved half a dozen groups from the northern and western desert, the Mexica among them.
