How everything came to be

"The Spanish assault on Mexico was set in motion by Diego Velásquez, the Spanish Governor of Cuba. By the early sixteenth century, the Spanish settlement in Cuba was mired in problems. Quite simply, there was neither enough land nor enough slave labour to meet the needs of a growing European population. Velásquez therefore sent expeditions into the Yucatán and the Gulf of Mexico between 1516 and 1518 to conduct reconnaissance missions in the surrounding area. Although the voyages did not yield an immediate solution for the Governor of Cuba, there were indications of a wealthy civilisation somewhere just beyond the Spaniard's reach. Intrigued and excited about the possibility of finding the source of this wealth, Velásquez commissioned Hernán Cortés to explore, trade, and search for Christian captives in the Yucatán."

Source