Trinidad is one of the two islands making up the Republic of Trinidad and Tobago, off the east coast of Venezuela. It covers an area of 5,000 km2 and is cut by the Northern and the Central Ranges, rising to respectively 900 and 300 m, while in the south are a series of low hills, termed the Southern Ranges. The intervening lowlands are partly swampy, giving the Caroni and Ortoire Swamps. The natural vegetation is tropical rain forest, but most of the lowlands are under cultivation, with sugarcane being a substantial cash crop. The island supports a population of one million people, which has increased by a factor of four over the last century, making it a crowded place with a density of 252/km2. The bulk of the population is of African and Indian origin, being the descendants of slaves and indentured labour brought in to work the sugar estates after the abolition of slavery. The remaining 20% are of mixed Spanish, French, Portuguese, English, Chinese and Amer-Indian descent.