The Nguyen lords chose Thua Thien, a northern territory of Thuan Hoa, as their family seat.[7] In 1687 during the reign of Nguyen lord- Nguyen Phuc Tran,[8] the construction of a citadel was started in Phu Xuan, a village in Thua Thien Province.[7][8] The citadel was a power symbol of Nguyen family rather than a defensive building because the Trịnh lords' army could not breach Nguyen lords' defense in the north regions of Phú Xuân.[7] In 1744, Phu Xuan officially became the capital of central and southern Vietnam after Nguyen lord- Nguyen Phuc Khoat proclaimed himseft Vo Vương (Vo King or Martial King in Vietnamese).[7] Among westerners living in the capital at this period was the Portuguese Jesuit João de Loureiro from 1752 onwards.[9]