Concept
The Nguyễn lords (, 主阮; 1558–1777, 1780–1802), also known as the Nguyễn clan (阮氏, Nguyễn thị), were the rulers of southern Đại Việt during the Revival Lê dynasty and ancestors of Nguyễn dynasty's emperors. The territory they ruled was known contemporarily as Đàng Trong (Inner Realm) and by Europeans as Cochinchina, in opposition to the Trịnh lords ruling northern Đại Việt, known then as Đàng Ngoài (Outer Realm). Both Nguyễn and Trịnh lords were de jure subordinates of the Lê dynasty. The Nguyễn lords were members of the House of Nguyễn Phúc. While they recognized the authority of and claimed to be loyal subjects of the revival Lê dynasty, they were de facto rulers of southern Đại Việt. Meanwhile, the Trịnh lords ruled northern Đại Việt in the name of the Lê emperor, who was in reality a puppet ruler. They fought a series of long and bitter wars that pitted the two halves of Vietnam against each other. The Nguyễn were finally overthrown in the Tây Sơn wars, but one of their descendants would eventually come to unite all of Vietnam. Their rule consolidated earlier southward expansion into Champa and pushed southwest into Cambodia. The Nguyễn lords traced their descent from a powerful clan originally based in Thanh Hóa Province. The clan supported Lê Lợi in his successful war of independence against the Ming dynasty. From that point on, the Nguyễn were one of the major noble families in Vietnam. Perhaps the most famous Nguyễn of this time was Nguyễn Thị Anh, the queen-consort for nearly 20 years (1442–1459). Lê–Mạc War In 1527, Mạc Đăng Dung overthrew the emperor Lê Cung Hoàng and established a new dynasty- the Mạc dynasty. The Trịnh and Nguyễn lords fled to Thanh Hóa province and refused to accept the rule of the Mạc. All of the region south of the Red River was under their control, but they were unable to dislodge the Mạc from Thăng Long for many years. During this time, the Nguyễn–Trịnh alliance was led by Nguyễn Kim; his daughter Nguyễn Thị Ngọc Bảo was married to the Trịnh clan leader, Trịnh Kiểm.