When the migration took place, Tezcuco, situated on the northeastern shore of the lake, became a dominant pueblo, and was at the head of a considerable confederacy. On the western side of the lake was another group of pueblos known as the Tecpanecs, who were rivals of Tezcuco. Here there settled about the year 1200 a vagrant tribe of the Chichimecs; the new arrivals were named by the Tecpanecs crane people or Aztecs, probably from their habit of wading in the marshy shores of the lake while engaged in fishing. The newcomers proved industrious, and in the course of time reclaimed the marshy island, building on the land two towns, the villages of Tenochtitlan (place of a prickly pear) and Tlatelolco (place of a hill). According to Aztec folklore, when they took possession of the island, they found on it a prickly pear tree growing on a rock and on this rock they saw an eagle devouring a snake. This fable is still recalled in the present arms of the republic of Mexico. The two Aztec pueblos on the lake remained distinct communities until 1473, a fact which suggests their being built on separate islands, according to the traditional account. By help of the Aztecs, who were skilled in the art of war, the Tecpanec confederacy made great advances in dominating the valley. There was a little contest with Tezcuco when the confederates demanded from its people the usual tribute of cotton cloth; Tezcuco was taken and handed over to the Aztecs as a reward for their valuable services. The growing importance of the island pueblos soon, however, aroused the jealousy of the Tecpanecs and they resolved to suppress the two island communities by transferring the inhabitants to the shores of the lake. In the war which followed, though many of the people of the islands were at first reluctant to try conclusions with their powerful neighbors, the counsels of their warlike leader, Ischohuatl, prevailed. Azcapozalco, the center of the Tecpanec confederacy was captured, and with this conquest, which took place in or about the year 1428, Tenochtitlan or Mexico became the dominant power in the valley.