トゥアティエン＝フエ省
The area ceased to be the southernmost of Đại Việt following the political marriage of the Trần Dynasty princess, Huyền Trân, to Champa king, Jaya Sinhavarman III (Vietnamese: "Chế Mân"). Princess Huyền Trân was king Trần Nhân Tông's daughter and king Trần Anh Tông's younger sister. Political matches made to acquire land was a traditional practice by Champa kings. Thanks to this marriage, Đại Việt acquired lands (as dowry) of what is now Quảng Trị Province and Thừa Thiên–Huế Province (provinces which were then known respectively as Chau O and Chau Ri or Chau Ly).