were not yet under a single chief who could lay claim to kinship with the ruling houses of other cities, and they were now under the protection of Azcapotzalco, to the ruler of which they paid tribute. Not long after their settlement, dissensions broke out among themselves, and certain clans removed to the small island of Tlaltelolco adjoining Tenochtitlan on the north. The split however was not final, and the two sections remained in close alliance, though under separate administration. The question of the dates of these various events is by no means easy to determine. Tenochtitlan, according to the Mendoza codex, which gives a continuous chronicle from this point, was founded in the year 2. calli (two house), or 1325, and this date may, I believe, be taken as reasonably exact. We are told that the Aztec were subject to Colhuacan for about twenty-five years, and that they spent half a century before that on the islands of Acocolco. If we allow about twenty years spent at Chapultepec and in the migration from Colhuacan to Tenochtitlan, we get 1230 as the approximate date of their arrival at the former city. At this time, according to legend, Nopaltzin, the successor of Xolotl, was ruling at Tenayocan, and the commencement of his reign cannot be put much earlier than 1 225, since we are told that Tlotzin, his successor (called Huetzin by Ixtlilxochitl), died in the year in which Tenochtitlan was founded. Xolotl, the founder of the "Chichimec" power, seems to have reigned long, and indeed the Mexican rulers as a whole seem to have been singularly long-lived. But in any case Xolotl cannot have led his followers into the Mexican valley much before the second half of the twelfth century. If the annals of Quauhtitlan are correct in assigning the year 1064 to the destruction of Tulan, then the statement that the Chichimec migration occurred some thirty years later must be an error. It is true that if the statements of Sahagun as to the length of the reigns of the
