Four Chinese characters - Thai Duc Thong Bao / Blank. 25mm, 3.46 grams. Issued 1778-1788.  Krause KM 137 (for type); Vietnamese Coins (National Museum of Vietnamese History, 2005) #230.

The Tây Sơn Rebellion (1771–1802) was a major uprising in Vietnam, led by the Tây Sơn brothers—most notably Nguyễn Huệ (later Emperor Quang Trung). It began as a peasant revolt in central Vietnam against corrupt local officials, heavy taxation, and feudal oppression but quickly grew into a full-scale civil war that toppled both the ruling Nguyễn lords in the south and the Trịnh lords in the north, who had divided the country for centuries.

The Tây Sơn forces also successfully repelled a major invasion by the Qing dynasty of China in 1789, securing Vietnamese independence. Nguyễn Huệ's military brilliance made him a national hero, but after his death in 1792, the Tây Sơn regime weakened. In 1802, Nguyễn Ánh, a surviving member of the Nguyễn royal family, with support from foreign allies, defeated the Tây Sơn and unified the country, founding the Nguyễn dynasty as Emperor Gia Long. The Tây Sơn Rebellion profoundly reshaped Vietnam’s political landscape and is remembered for its social reforms and nationalist significance.