evidence: Singapore, city-state located at the southern tip of the Malay Peninsula, about 85 miles (137 kilometres) north of the Equator. It consists of the diamond-shaped Singapore Island and some 60 small islets; the main island occupies all but about 18 square miles of this combined area. The main island is separated from Peninsular Malaysia to the north by Johor Strait, a narrow channel crossed by a road and rail causeway that is more than half a mile long. The southern limits of the state run through Singapore Strait, where outliers of the Riau-Lingga Archipelago—which forms a part of Indonesia—extend to within 10 miles of the main island. Singapore is the largest port in Southeast Asia and one of the busiest in the world. It owes its growth and prosperity to its focal position at the southern extremity of the Malay Peninsula, where it dominates the Strait of Malacca, which connects the Indian Ocean to the South China Sea. Once a British colony and now a member of the Commonwealth, Singapore first joined the Federation of Malaysia on its formation in 1963 but seceded to become an independent state on August 9, 1965.