The Nguyen lords chose Thua Thien, a northern territory of Thuan Hoa, as their family seat. In 1687 during the reign of Nguyen lord- Nguyen Phuc Tran, the construction of a citadel was started in Phu Xuan, a village in Thua Thien Province. 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. 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). Among westerners living in the capital at this period was the Portuguese Jesuit João de Loureiro from 1752 onwards.