The islands of the Caribbean. Columbus, who in 1492 was the first European to reach the islands, called them the West Indies because he believed he had arrived near India by travelling westward. The islands were opened up by the Spanish in the 16th century and thereafter were the theatre of rivalry between the European colonial powers. Cultivation of sugar was introduced and the population was transformed by the mass importation of West African slaves to work the agricultural plantations; their descendants form the largest group in the population.