Vietnam (, ; Việt Nam ), officially the Socialist Republic of Vietnam (Cộng hòa xã hội chủ nghĩa Việt Nam), is the easternmost country on the Indochina Peninsula. With an estimated million inhabitants, it is the 15th most populous country in the world. Vietnam is bordered by China to the north, Laos and Cambodia to the west, part of Thailand to the southwest, and the Philippines, Malaysia, and Indonesia across the South China Sea to the east and southeast. Its capital city has been Hanoi since the reunification of North and South Vietnam in 1976, while its most populous city is Ho Chi Minh City.
During the 3rd century BC, ancient Vietnamese people inhabited modern-day northern Vietnam and established the state of Âu Lạc. The independent state was annexed by Nam Việt in 179 BC. Nam Việt was subsequently annexed by the Han Empire and became part of Imperial China for over a millennium from 111 BC to 939 AD. An independent Vietnamese state emerged in 939 following Vietnamese victory in the battle of Bạch Đằng against the Southern Han. Successive Vietnamese imperial dynasties flourished as the nation expanded geographically and politically into Southeast Asia until the Indochina Peninsula was colonised by the French in the mid-19th century.