Question: Which country Thuận Thiên (Trần Dynasty Empress)'s mother is from?
Sentence (from "Thuận Thiên (Trần dynasty empress)"): Empress Thuận Thiên (Lý Ngọc Oanh) (1216–1248) was the second empress of Trần dynasty, she succeeded her younger sister Empress Chiêu Thánh in 1237 by an arrangement of Trần Thủ Độ in which Prince Hoài Trần Liễu was forced to give up his 3-month pregnant wife Princess Thuận Thiên to the Emperor Trần Thái Tông.
Relevant evidence: No