XOLOTL (soh-lotl'), "the vigilant," also surnamed " the great," founder of the Mexican dynasty of Tenayucan, or Texcoco, lived in the 12th century. He was chief of the Chichimec tribes that invaded Anahuac after the destruction of the Toltec monarchy, and, settling on the lake of Texcoco, he proclaimed himself king, about 1160. He recognized that the subjugated Toltecs, as well as the tribes of Aculhuas and Tecpanecs that arrived afterward in the valley were far superior to his own wild and warlike nation, and he therefore treated them kindly, so that they soon transformed the Chichimecs into a civilized race. To equalize the different tribes and dialects, he ordered the Nahuatl, or instructed, dialect, a form of the Toltec, to be adopted as the official language, which in time superseded all others, and is the equivalent of what is now generally called Aztec. King Xolotl constructed in Texcoco a temple to the sun, a palace, and gardens, and made that city the centre of the civilization of Anahuac. He married his daughters to the two principal chiefs of the Aculhuas, who became founders of the empire of Atzcapotzalco, and was succeeded about 1220 by his son, Nopaltzin.