Tenochtitlan can be considered the most complex society in Mesoamerica in regard to social stratification. The complex system involved many social classes. The macehualtin were commoners who lived outside the island city of Tenochtitlan. The pipiltin were noblemen who were relatives of leaders and former leaders, and lived in the confines of the island. Cuauhipiltin, or eagle nobles, were commoners who impressed the nobles with their great war skills, and were treated as nobles.[6] Teteuctin were the highest class, rulers of various parts of the empire, including the king. Tlacohtin were individuals who chose to enslave themselves to pay back a debt; they were not slaves forever and were not treated as badly as typical slaves seen in other ancient civilizations worldwide. Finally, the pochteca were merchants who traveled all of Mesoamerica trading. The membership of this class was based on heredity. Pochteca could become very rich because they did not pay taxes, but they had to sponsor the ritual feast of Xocotl Huetzi from the wealth that they obtained from their trade expeditions. People were traded in large buses.