History of the Americas in the context of "Spectroradiometer"

In the history of the Americas, the pre-Columbian era, also known as the pre-contact era, or as the pre-Cabraline era specifically in Brazil, spans from the initial peopling of the Americas in the Upper Paleolithic to the onset of European colonization, which began with Christopher Columbus's voyage in 1492. This era encompasses the history of Indigenous cultures prior to significant European influence, which in some cases did not occur until decades or even centuries after Columbus's arrival.

During the pre-Columbian era, many civilizations developed permanent settlements, cities, agricultural practices, civic and monumental architecture, major earthworks, and complex societal hierarchies. Some of these civilizations had declined by the time of the establishment of the first permanent European colonies, around the late 16th to early 17th centuries, and are known primarily through archaeological research of the Americas and oral histories. Other civilizations, contemporaneous with the colonial period, were documented in European accounts of the time. For instance, the Maya civilization maintained written records, which were often destroyed by Christian Europeans such as Diego de Landa, who viewed them as pagan but sought to preserve native histories. Despite the destruction, a few original documents have survived, and others were transcribed or translated into Spanish, providing modern historians with valuable insights into ancient cultures and knowledge.

The Spanish conquest of the Aztec Empire was a pivotal event in the history of the Americas, marked by the collision of the Aztec Triple Alliance and the Spanish Empire, with the latter being supported by its Indigenous allies. Taking place between 1519 and 1521, this event saw the Spanish conquistador Hernán Cortés, and his small army of European soldiers and numerous Indigenous allies, overthrowing one of the most powerful empires in Mesoamerica.

Led by the Aztec ruler Moctezuma II, the Aztec Empire had established dominance over central Mexico through military conquest and intricate alliances. Because the Aztec Empire ruled via hegemonic control by maintaining local leadership and relying on the psychological perception of Aztec power—backed by military force—the Aztecs normally kept subordinate rulers compliant. This was an inherently unstable system of governance, as this situation could change with any alteration in the status quo. A combination of factors including superior weaponry, strategic alliances with oppressed or otherwise dissatisfied or opportunistic Indigenous populations, and the impact of European diseases contributed to the downfall of the short rule of the Aztec civilization. In 1520, the first wave of smallpox killed 5–8 million people.