The Tây Sơn dynasty (, (Chữ Nôm: 茹西山); (Hán tự: 西山朝) was a ruling dynasty of Vietnam, founded in the wake of a rebellion against both the Nguyễn lords and the Trịnh lords before subsequently establishing themselves as a new dynasty. The Tây Sơn were led by three brothers, referred to by modern Vietnamese historians as the Tây Sơn brothers because of their origin in the district of Tây Sơn. The Tây Sơn dynasty ended the century-long war between the Trịnh and Nguyễn families, fought off an attack by Qing China, and united the country for the first time in 200 years. Under the most prominent of the Tây Sơn brothers, Nguyễn Huệ—later the emperor Quang Trung—Vietnam experienced an age of relative peace and prosperity. His heir, however, was not capable of properly ruling the country, allowing the exiled Nguyễn lord Nguyễn Ánh to retake the south of Vietnam and eventually pave the way for his own imperial dynasty, the Nguyễn dynasty. Name The Tây Sơn dynasty was named after the Tây Sơn District in Bình Định Province, the birthplace of the three brothers who established the dynasty. The name "Tây Sơn" means "western mountains". History Background In the 18th century, Vietnam was officially ruled by the Lê dynasty, but real power lay in the hands of two warring families, the Trịnh lords of the north who ruled from the imperial court in Thăng Long and the Nguyễn lords in the south, who ruled from their capital Huế. Both sides warred extensively for control of the country while simultaneously claiming to be loyal to the Lê emperor. Life for the peasants during these times were difficult- ownership of land became concentrated in the hands of a handful of landlords as time passed. The imperial bureaucracy became corrupt and oppressive; at one point the imperial examination-degrees were sold to whoever was wealthy enough to purchase them. As the people grew poorer, the ruling lords lived lavish lifestyles in opulent palaces. While the Trịnh lords had enjoyed peace since the end of the war between the Trịnh and the Nguyễn in 1672, the Nguyễn lords regularly campaigned against Cambodia and later the Kingdom of Siam. While the Nguyễn lords usually won these wars and opened up new fertile lands for the landless poor to settle, the frequent warring took a toll on their popularity. Conquest of Nguyễn lords In 1769 the new