instruction and military training. A second, more prestigious type of school called a "" served to teach the nobility, as well as commoners of high standing seeking to become priests or artisans. Moctezuma also created a new title called "" that could be conferred on commoners. This title was a form of non-hereditary lesser nobility awarded for outstanding military or civil service (similar to the English knight). Commoners who received this title rarely married into royal families and became kings. One component of this reform was the creation of an institution of regulated warfare called the Flower Wars. Mesoamerican warfare overall is characterized by a strong preference for capturing live prisoners as opposed to slaughtering the enemy on the battlefield, which was considered sloppy and gratuitous. The Flower Wars are a potent manifestation of this approach to warfare. These highly ritualized wars ensured a steady, healthy supply of experienced Aztec warriors as well as a steady, healthy supply of captured enemy warriors for sacrifice to the gods. Flower wars were pre-arranged by officials on both sides and conducted specifically for the purpose of each polity collecting prisoners for sacrifice. Native historical accounts say that these wars were instigated by Tlacaelel as a means of appeasing the gods in response to a massive drought that gripped the Basin of Mexico from 1450 to 1454. The flower wars were mostly waged between the Aztec Empire and the neighboring cities of their arch-enemy Tlaxcala. Early years of expansion After the defeat of the Tepanecs, Itzcoatl and Nezahualcoyotl consolidated power in the Basin of Mexico and began to expand beyond its borders. The first targets for imperial expansion were Coyoacan in the Basin of Mexico and Cuauhnahuac and Huaxtepec in the modern Mexican state of Morelos. These conquests provided the new empire with a large influx of tribute, especially agricultural goods. Itzcoatl died, and Moctezuma I was enthroned as the new Mexica emperor. The expansion of the empire was briefly halted by a major four-year drought that hit the Basin of Mexico in 1450, and several cities in Morelos had to be re-conquered after the drought subsided. Moctezuma and Nezahualcoyotl continued to expand the empire east towards the Gulf of Mexico and south into Oaxaca. In 1468, Moctezuma I died and was succeeded by his son Axayacatl. Most of Axayacatl's thirteen-year reign was spent consolidating the territory acquired under his predecessor. Motecuzoma and Nezahualcoyotl