From roughly 600 CE in the middle of the Maya Classic period, it was a major city, achieving its greatest growth and power after the Maya sites of the central lowlands to the south had already collapsed. The Postclassic occupation at the site saw extensive additions of structures and motifs in a style more reminiscent of Central Mexican "Toltec" cultures. This was once thought to have been representative of direct migration or even conquest from central Mexico, but most contemporary interpretations view the presence of these "non-Maya" styles more as the result of cultural diffusion. Revolt and civil war among the Maya in 1221 CE, evidenced by archeological findings of burned buildings, led to Chichen Itza's decline and rulership over Yucatán shifted to Mayapan.