Phú Xuân

Phú Xuân(富春) was the historic capital of the Nguyễn Lords, the Tây Sơn Dynasty, and later became the Nguyễn Dynasty's capital in Huế.

In 1306, the King of Champa Chế Mân offered Vietnam two Chăm prefectures, Ô and Lý, in exchange for marriage with a Vietnamese princess named Huyền Trân. The Vietnamese King Trần Anh Tông accepted this offer. He took and renamed Ô and Lý prefectures to Thuận prefecture and Hóa prefecture, respectively, with both of them often referred to as Thuận Hóa region.

In 1592, the Mạc Dynasty was forced to flee to Cao Bằng and the Lê emperors were enthroned as de jure Vietnamese rulers under the leadership of Nguyễn Kim, the leader of Lê Dynasty loyalists. Later, Kim was poisoned by a Mạc Dynasty general which paved the way for his son-in-law, Trịnh Kiểm, to take over the leadership. Kim's eldest son, Nguyễn Uông, was also assassinated in order to secure Trịnh Kiểm's authority.Nguyễn Hoàng, another son of Nguyễn Kim, feared a fate like Nguyễn Uông's so he pretended to have mental illness. He asked his sister Ngoc Bao, who was a wife of Trịnh Kiểm, to entreat Kiểm to let Hoàng govern Thuận Hóa, the furthest south region of Vietnam at that time.

Because Mạc Dynasty loyalists were revolting in Thuận Hóa and Trịnh Kiểm was busy fighting the Mạc Dynasty forces in northern Vietnam during this time, Ngoc Bao's request was approved and Nguyễn Hoàng went south. After Hoàng pacified Thuận Hóa, he and his heir Nguyễn Phúc Nguyên serectly made this region loyal to the Nguyễn family; then they rose against the Trịnh Lords. Vietnam erupted into a new civil war between two de facto ruling families: the clan of the Nguyễn Lords and the clan of the Trịnh Lords.

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Wikipedia