Nguyen dynasty and South Vietnam

The Nguyễn dynasty (Vietnamese: Nhà Nguyễn, chữ Nôm: 茹阮) was the last Vietnamese dynasty, preceded by the Nguyễn lords and ruling unified Vietnam independently from 1802 until the start of the French protectorate in 1883. Its emperors were members of the House of Nguyễn Phúc. During its existence, the Nguyễn empire expanded into modern-day Southern Vietnam, Cambodia, and Laos through a continuation of the centuries-long Nam tiến and Siamese–Vietnamese wars. With the French conquest of Vietnam, the Nguyễn dynasty was forced to give up sovereignty over parts of Southern Vietnam (Cochinchina) to France in 1862 and 1874, and after 1883 the Nguyễn dynasty only nominally ruled the French protectorates of Annam (Central Vietnam) as well as Tonkin (Northern Vietnam). Backed by Imperial Japan, in 1945 the last Nguyễn emperor Bảo Đại abolished the protectorate treaty with France and proclaimed the Empire of Vietnam for a short time until 25 August 1945.

The Republic of Vietnam (RVN; Vietnamese: Việt Nam Cộng hòa, VNCH), commonly known as South Vietnam, was a country in Southeast Asia that existed from 1955 to 1975. It first garnered recognition in 1949 as the associated State of Vietnam within the French Union, with its capital at Saigon. Since 1950, it was a member of the Western Bloc during the Cold War. Following the 1954 partition of Vietnam, it became known as South Vietnam and was established as a republic in 1955. Although South Vietnam failed to gain admission into the United Nations as a result of a Soviet veto in 1957, its sovereignty was recognized by 95 countries as of January 1975. It was succeeded by the communist-controlled Republic of South Vietnam in 1975. In 1976, North Vietnam and the Republic of South Vietnam merged to form the Socialist Republic of Vietnam.