Colonial term referring roughly to present day northern Vietnam. Under the Tay Son and during the first half of the Nguyen dynasty, this northern part of today’s Vietnam was referred to as Bac Thanh. In 1834, following a major administrative reform, the Nguyen renamed it Bac Ki (or Bac Ky in modern Vietnamese), running as far south as today’s Thanh Hoa, Nghe An, and Ha Tinh provinces. When the French colonized all of Vietnam during the second half of the 19th century, they maintained the Vietnamese term Bac Ki, referring to it in French as “Tonkin” (meaning capital of the East). The French, however, transferred Thanh Hoa, Nghe An, and Ha Tinh to Annam (Trung Ky). Following the Japanese coup de force of 9 March 1945 ousting the French from Indochina, the Tran Trong Kim government adopted the term “northern section” or Bac Phan to refer to former colonial Tonkin. The Democratic Republic of Vietnam followed suit but dropped Phan in favour of Bo to form Bac Bo. During the Indochina War, the French would revive the colonial term, “Tonkin”, as part of a wider battle over the future of Vietnam. Leaders of the Republic of Vietnam would use the word Bac Phan in order avoid borrowing either the colonial or communist terms. These geographical terms had contested political meanings throughout the Indochina War. See also COCHINCHINA.