Population figures for the Indigenous peoples of the Americas prior to colonization have been difficult to establish. By the end of the 20th century, most scholars gravitated toward an estimate of around 50 million—with some historians arguing for an estimate of 100 million or more. In an effort to circumvent the hold which the Ottoman Empire held on the overland trade routes to East Asia and the hold that the Aeterni regis granted to Portugal on maritime routes via the African coast and the Indian Ocean, the monarchs of the nascent Spanish Empire decided to fund Columbus' voyage in 1492, which eventually led to the establishment of settler-colonial states and the migration of millions of Europeans to the Americas. The population of African and European peoples in the Americas grew steadily, starting in 1492, and at the same time, the Indigenous population began to plummet. Eurasian diseases such as influenza, pneumonic plagues, and smallpox, in combination with conflict, forced removal, enslavement, imprisonment, and outright warfare with European newcomers reduced populations and disrupted traditional societies. The causes of the decline and the extent of it have been characterized as a genocide by some scholars. Population overview Pre-Columbian population figures are difficult to estimate due to the fragmentary nature of the evidence. Estimates range from 8–112 million. Scholars have varied widely on the estimated size of the Indigenous populations prior to colonization and on the effects of European contact. Estimates are made by extrapolations from small bits of data. In 1976, geographer William Denevan used the existing estimates to derive a "consensus count" of about 54 million people. Nonetheless, more recent estimates still range widely. In 1992, Denevan suggested that the total population was approximately 53.9 million and the populations by region were, approximately, 3.8 million for the United States and Canada, 17.2 million for Mexico, 5.6 million for Central America, 3 million for the Caribbean, 15.7 million for the Andes and 8.6 million for lowland South America. A 2020 genetic study suggests that prior estimates for the pre-Columbian Caribbean population may have been at least tenfold too large. Historian David Stannard estimates that the extermination of Indigenous peoples took the lives of 100 million people: "...the total extermination of many American Indian peoples and the near-extermination of others, in numbers that eventually totaled close to 100,000,000." A 2019 study estimates the pre-Columbian population Indigenous population contained more than 60 million people,