Who arrived in Mexico and found groups of Native Americans who are willing to help him by the Aztecs?

Hernán Cortés arrived in Mexico in 1519 and encountered various Indigenous groups who were discontent with Aztec rule. Among those who aided him were the Tlaxcalans, who saw an opportunity to rebel against the Aztecs and formed an alliance with Cortés. This support was instrumental in his eventual conquest of the Aztec Empire.