(rē'ou, rē'ō) , island group (1990 pop. 568,019), 2,280 sq mi (5,905 sq km), Indonesia, at the entrance to the Strait of Malacca, separated from Malaya by the Strait of Singapore. Its largest island, Bintan, has extensive bauxite and tin deposits, is being developed as a tourist destination, and is the site of Tanjung Pinang (1980 pop. 36,999), chief city of the group. Together with the Lingga Archipelago to the south, it forms the Riau-Lingga Archipelago of Indonesia.