Christopher Columbus
Since the late 20th century, historians have criticized Columbus for initiating colonization and for abuse of natives. Among reasons for this criticism is the poor treatment of the native Taíno people of Hispaniola, whose population declined rapidly after contact with the Spanish. Columbus required the natives to pay tribute in gold and cotton. Modern estimates for the pre-Columbian population of Hispaniola are around 250,000–300,000. According to the historian Gonzalo Fernandez de Oviedo y Valdes, by 1548, 56 years after Columbus landed, and 42 years after he died, fewer than 500 Taíno were living on the island. The indigenous population declined rapidly, due primarily to the first pandemic of European endemic diseases, which struck Hispaniola after 1519. The natives had no acquired immunity to these new diseases and suffered high fatalities. There is also documentation that they were overworked.
Guanches
Strictly speaking, the Guanches were the indigenous peoples of Tenerife. The population seems to have lived in relative isolation up to the time of the Castilian conquest, around the 14th century (though Genoese, Portuguese, and Castilians may have visited there from the second half of the 8th century onwards). The name came to be applied to the indigenous populations of all the seven Canary Islands, those of Tenerife being the most important or powerful.