The Principality of Hà Tiên or Hà Tiên Protectorate, was a de facto independent principality in the mouth of Mekong Delta, later a vassal principality of the Siamese Rattanakosin Kingdom and Vietnamese Nguyễn dynasty in the 18th and 19th century before being annexed by Vietnam in 1832. The principality located on present-day Cambodia–Vietnam border. It was ruled by Chinese refugees. The name of the principality was variously spelled as Hexian Zhen, Nangang, Gangkou, Bendi or Kundama in Chinese, Phutthaimat or Banthaimat in Thai, Ponthiamas, Pontheaymas and Pontiano in French, Panthai-mas, Bantaimas, Pontiamas, Pontaimas, Bantay-mas, Banteay M'eas, Pontiamas, Pontiamasse, Po-taimat, Can Cao, Cancar, and infinite other variations. Many of the pronunciations were similar to Banteay Meas, thus confusing Hà Tiên with a nearby town Banteay Meas.
History
Hà Tiên and its nearby area had been a part of Cambodia for a long time. In 18 century, a Chinese refugee, Mo Jiu, was granted the Khmer title Oknha by Cambodian king. He was allowed to build a small town in the mouth of Mekong Delta. The colonial town was known as Hà Tiên in Vietnamese sources, while Cambodian called it Peam. This area had a dual political structure: Mạc Cửu ruled Chinese and Vietnamese; while local Khmers continued to be ruled by a Khmer governor, called Oknha Reacheasetthi. However, Siamese sources called the Hà Tiên rulers Phraya Rachasethi, thus confusing them with the Khmer governor. Mạc Cửu switched allegiance to the Nguyễn lords of Vietnam in 1707, just after an invasion by Siam. He received the Vietnamese rank hầu from Nguyễn lords. Since then, Hà Tiên was treated as a semi-autonomous region of Vietnam. However, as a vassal of Cambodia, Hà Tiên still paid taxes to Cambodian court. Mạc Cửu died in 1736, his son Mạc Thiên Tứ succeeded. A Cambodian army invaded Hà Tiên in 1739 but was utterly defeated. From then on, Cambodia did not try to resume Hà Tiên, Hà Tiên enjoyed full independence from Cambodia thereafter. Mạc Thiên Tứ's reign saw the golden age of Hà Tiên. In 1758, Hà Tiên established Outey II as puppet king of Cambodia. After War of the second fall of Ayutthaya, Mạc Thiên Tứ tried to install Prince Chao Chui as the new Siamese king, but was defeated by Taksin. Hà Tiên was completely devastated by Siamese troops in 1771, Mạc Thiên Tứ had flee to Trấn Giang. In there, he was sheltered by Nguyễn lord. Two years later, Siamese army withdrew from Hà Tiên, and Mạc Thiên Tứ retook his principality. After Tây Sơn rebellion broke out, Hà Tiên supported Nguyễn lords. Nguyễn lords' regime was overthrown in 1777, Mạc Thiên Tứ refused to surrender to Tây Sơn rebels, and fled to Siam. He was thrown into prison by Taksin in 1780, most of his family members were executed. In this situation, a power vacuum developed. After Rama I crowned the new Siamese king in 1782, a Siamese general Phraya Thatsada was sent to capture Hà Tiên. The town was occupied by rebels but soon was captured by Nguyễn Ánh. However, Ánh had to abandon it because he was attacked by Tây Sơn army. In 1785, a Siamese army under Krom Luang Thepharirak was sent to help Nguyễn Ánh. In the same time, Mạc Tử Sinh was sent back to Hà Tiên by Rama I. When the Siamese fleet landed in Banteay Meas, an army under Mạc Tử Sinh and Phraya Thatsada was to reinforce them. However, Siamese fleet was defeated by Tây Sơn army in Battle of Rạch Gầm-Xoài Mút. Mạc Tử Sinh and Nguyễn Ánh fled to Siam. Nguyễn Ánh returned to Vietnam and retook Gia Định in 1787. In the same time, Mạc Tử Sinh was sent back to help Nguyễn Ánh. Chinese researcher Dai Kelai stated that Mạc Tử Sinh was probably a puppet ruler installed by Siam. Not long after Mạc Tử Sinh died, Ngô Ma briefly served as acting ruler. Ngô Ma was probably the same person Thông ngôn A Ma, a Siamese who served as a Vietnamese interpreter during Taksin's reign. Maha Sura Singhanat appointed Mạc Công Bính as the new ruler of Hà Tiên in 1789. However, when Mạc Công Bính arrived in Vietnam, Nguyễn Ánh appointed him the governor of Long Xuyên. It made Singhanat very angry, Nguyễn Ánh had to send him back to Hà Tiên. Mạc Công Bính died in 1792; two generals, Trần Hanh and Trần Tô were appointed acting rulers by Siam. In 1800, Mạc Tử Thiêm was appointed the new ruler by Siam, and sent back to Hà Tiên. Since 1803, Hà Tiên was subjected to the jurisdiction of the Viceroyalty of Gia Định. Mạc Tử Thiêm went to Bangkok to attend Anurak Devesh's funeral in 1807. During his absence, Mạc Công Du was appointed the acting ruler by Nguyễn Ánh. Mạc Tử Thiêm died in 1809. Since then, Vietnamese Nguyễn dynasty managed to appoint the ruler of Hà Tiên directly. Feared of provoking Siamese, Ngô Y Nghiễm and Lê Tiến Giảng were appointed quyền lĩnh trấn sự instead of trấn thủ. The Vietnamese managed to eliminate the influence of Mạc family in this area. In 1818, Mạc Công Du was appointed the ruler of Hà Tiên, however, he was only an official under Nguyễn dynasty. Mạc Công Du retired in 1829, his younger brotherMạc Công Tài succeeded. Hà Tiên trấn was disestablished in 1832. Hà Tiên Province was formed in its area. Lê Văn Khôi revolt broke out in 1833, Mạc Công Du, Mạc Công Tài, their sons Mạc Hầu Hy and Mạc Hầu Diệu, accepted official posts from rebels. All of them were arrested and taken to Huế. In the same year, Mạc Công Du and Mạc Công Tài died in prison. Later, Mạc Hầu Hy fled to Siam.
