structural:summarization
Nguyễn dynasty rule

In 1679, Lord Nguyễn Phúc Tần allowed a group of Chinese refugees from the Qing dynasty to settle in Mỹ Tho, Biên Hòa and Saigon to seek refuge.In 1698, Nguyễn Hữu Cảnh, a Vietnamese noble, was sent by the Nguyễn rulers of Huế by sea to establish Vietnamese administrative structures in the area, thus detaching the area from Cambodia, which was not strong enough to intervene. He is often credited with the expansion of Saigon into a significant settlement. King Chey Chettha IV of Cambodia tried to stop the Vietnamese but was defeated by Nguyễn Hữu Cảnh in 1700. In February 1700, he invaded Cambodia from An Giang. In March, the Vietnamese expedition under Cảnh and a Chinese general Trần Thượng Xuyên (Chen Shangchuan) defeated the main Cambodian army at Bích Đôi citadel, king Chey Chettha IV took flight while his nephew Ang Em surrendered to the invaders, as the Vietnamese marched onto and captured Cambodia's capital Phnom Penh. As a result, Saigon and Long An were officially and securely obtained by the Nguyễn, more Vietnamese settlers moved into the new conquered lands.

In 1788, Nguyễn Ánh captured the city, and used it as a centre of resistance against Tây Sơn. Two years later, a large Vauban citadel called Gia Định, or Thành Bát Quái ("Eight Diagrams") was built by Victor Olivier de Puymanel, one of the Nguyễn Ánh's French mercenaries. The citadel was captured by Lê Văn Khôi during his revolt of 1833–35 against Emperor Minh Mạng. Following the revolt, Minh Mạng ordered it to be dismantled, and a new citadel, called Phụng Thành, was built in 1836. In 1859, the citadel was destroyed by the French following the Battle of Kỳ Hòa. Initially called Gia Định, the Vietnamese city became Saigon in the 18th century.