Sumba, island, one of the Lesser Sunda Islands, southern Nusa Tenggara Timur provinsi (East Nusa Tenggara province), southern Indonesia, in the Indian Ocean across the Sumba Strait from Flores and west of Timor across the Savu Sea. Sumba has an area of 4,306 square miles (11,153 square km) and mountains up to 4,000 feet (1,220 metres) high but no volcanoes; its rivers are largely unnavigable. The annual rainfall of about 64 inches (1,625 mm) results in light forestation and much grassland, which feeds the fine Sandalwood breed of horse and the Ongole cattle, both more common in the east. Sumba’s woven cloth is famous for its design. Corn (maize) is the main crop, but rice, coffee, fruit, tobacco, coconuts, and vegetables are grown, and copra is exported; paddy rice is more common in the western half of the island. Most inhabitants are animists, though some are Muslims and Christians. Polygamy is fairly common among the upper classes.
Forests of sandalwood, now mostly depleted, attracted attention to the island in the 17th century. Treaties with the Dutch were concluded in 1756 and again between 1845 (when the first Dutch official came to reside on the island) and 1874, but difficulties persisted with the inhabitants because of piracy and slave raids. The chief town is Waingapu, located on the northern coast; it has a good anchorage and an airport. Waikabubak is the administrative centre for the western part of the island, and Waikelo, in the northwest, is the chief port for that area.