Vietnam Topic PageOfficially Socialist Republic of Vietnam, republic (2005 est. pop. 83,536,000), 128,400 sq mi (332,642 sq km), Southeast Asia. Occupying the eastern coastline of the Southeast Asian peninsula, Vietnam is bounded by China on the north, by Laos and Cambodia on the west, and by the Gulf of Tonkin and the South China Sea on the east and south. The capital is Hanoi and the largest city is Ho Chi Minh City, formerly Saigon.