Emperor Minh Mạng was the fourth son of Emperor Gia Long; his mother was Trần Thị Đang, second wife of Gia Long (confered Empress Dowager Nhân Tuyên later). Three eldest son of Gia Long, Crown prince Nguyễn Phúc Cảnh, "Duke of Thuận An" Nguyễn Phúc Hy and prince Nguyễn Phúc Tuấn, had died before their father, so Minh Mạng was the eldest son of Gia Long at that time.