This word was first coined by the Chinese to refer to the “Pacified South” (An Nam), the ethnic Viet Kingdom situated on the Chinese Middle Kingdom’s southern flank. However, under the French, this word acquired several confusing yet geopolitically important meanings. On the one hand, the French borrowed the Chinese term “Annam” to refer to the ethnic Viet Kingdom unified by the Nguyen Dynasty in the early 19th century. On the other hand, by colonizing “Annam” during the second half of the 19th century, the French divided it into three colonial territorial subunits: Cochinchina (Nam Ky) referred to the French colony consisting of what is roughly southern Vietnam today, Tonkin (Bac Ky) referred to the protectorate established over the north, while the French used the term Annam (Trung Ky) to refer to the protectorate they imposed upon the Nguyen Dynasty and now limited to central Vietnam.
Despite the division of the Nguyen Kingdom into three colonial parts, the French still needed a term with which to refer generally to all of the ethnic Viet people living in Cochinchina, Annam, and Tonkin. They thus continued to use the term “Annam” and “Annamese” to refer, often confusedly, to what today would be considered to be “Vietnam” and the “Vietnamese”. However, “Vietnam” did not exist during the colonial period, except in nationalist minds. This began to change following Bao Dai’s proclamation of Vietnamese independence on 11 March 1945, made possible by the Japanese overthrow of the French on 9 March 1945. The short-lived Tran Trong Kim government maintained its usage, as did Ho Chi Minh who announced the birth of the Democratic Republic of Vietnam on 2 September 1945. Vietnam now referred to an independent and unified territorial unit.
And as the French moved to restore colonial rule, so too did the word “Annam” enter into fierce competition with the national term “Vietnam” whose citizens were now legally defined as “Vietnamese”. The Vietnamese also decolonized the colonial terms for the north, the center, and the south, referring to them as Bac Bo (Tonkin), Trung Bo (Annam), and Nam Bo (Cochinchina).
That words counted in the Indochina War was clear following the outbreak of full-scale war in Vietnam on 19 December 1946, when the French High Commissioner for Indochina Georges Thierry d’Argenlieu, issued secret orders in January 1947 prohibiting his subordinates from using the word “Vietnam”. He instructed them to use Cochinchina, Annam, and Tonkin, and “Annamese” or “pays annamites” when referring to all the ethnic Viet living in all three regions (pays). See also LANGUAGE OF WAR.