In 1592, the Mac dynasty was forced to flee to Cao Bang province and the Le emperors were enthroned as "de jure" Vietnamese rulers under the leadership of Nguyen Kim, the leader of Le Dynasty loyalists. Later, Kim was poisoned by a Mạc Dynasty general which paved the way for his son-in-law, Trinh Kiem, to take over the leadership. Kim's eldest son, Nguyen Uông, was also assassinated in order to secure Trinh Kiem's authority. Nguyen Hoang, another son of Nguyen Kim, feared a fate like Nguyen Uong's so he pretended to have mental illness. He asked his sister Ngoc Bao, who was a wife of Trinh Kiem, to entreat Trinh Kiem to let Nguyen Hoang govern Thuan Hoa, the furthest south region of Vietnam at that time.