Background: The overseas expansion under the crown of Castile was initiated under the royal authority and first accomplished by the Spanish conquistadores. The Americas were incorporated into the Spanish Empire, with the exception of Brazil and Canada, and the crown created civil and religious structures to administer the region. The motivations for colonial expansion were trade and the spread of the Catholic faith through indigenous conversions. Beginning with the 1492 arrival of Christopher Columbus in the Caribbean and continuing control of vast territory for over three centuries, the Spanish Empire would expand across the Caribbean Islands, half of South America, most of Central America and much of North America (including present day Mexico, Florida and the Southwestern and Pacific Coastal regions of the United States).
Context: The Spanish conquest of Mexico is generally understood to be the Spanish conquest of the Aztec Empire (1519-21) which was the base for later conquests of other regions. Later conquests were protracted campaigns with less spectacular results than the conquest of the Aztecs. The Spanish conquest of Yucatan, the Spanish conquest of Guatemala, the war of Mexico's west, and the Chichimeca War in northern Mexico expanded Spanish control over territory and indigenous populations. But not until the Spanish conquest of Peru was the conquest of the Aztecs matched in scope by the victory over the Inca empire in 1532.  The Spanish conquest of the Aztec empire was led by Hernan Cortes. The victory over the Aztecs was relatively quick, from 1519 to 1521, and aided by his Tlaxcala and other allies from indigenous city-states or altepetl. These polities allied against the Aztec empire, to which they paid tribute following conquest or threat of conquest, leaving the city-states' political hierarchy and social structure in place.  The Spanish conquest of Yucatan was a much longer campaign, from 1551 to 1697, against the Maya peoples in the Yucatan Peninsula of present-day Mexico and northern Central America. Hernan Cortes' landing ashore at present day Veracruz and founding the Spanish city there on April 22, 1519 marked the beginning of 300 years of Spanish hegemony over the region. The assertion of royal control over the Kingdom of New Spain and the initial Spanish conquerors took over a decade, with importance of the region meriting the creation of the Viceroyalty of New Spain. Established by Charles V in 1535, the first viceroy was Don Antonio de Mendoza.  Spain colonized and exerted control of Alta California through the Spanish missions in California until the Mexican secularization act of 1833.
Question: When did the colonization of Mexico begin?. Whats the answer?
The Spanish conquest of Mexico is generally understood to be the Spanish conquest of the Aztec Empire (1519-21) which was the base for later conquests of other regions.