Chey Chettha IV^[1] (1656–1725), bornAng Sor, was aCambodian king for several periods in Cambodia's history (r. 1675–1695, 1696–1700, 1701–1702, 1705–1706).

He was the second son ofBarom Reachea V and also a younger brother ofKaev Hua II. Vietnamese army attackedPhnom Penh, the king Kaev Hua II fled into forest. Ang Sor surrendered to Vietnamese. He was crowned the Cambodian king by Vietnamese, whileAng Nan (Padumaraja IV) was crowned the vice king (uparaja). Chey Chettha IV occupiedLongvek, Padumaraja IV occupied Prey Nokor (Saigon). Both of them paid tribute to VietnameseNguyễn lord.^[2]

In 1687, he temporarily abdicated in favour of his motherQueen Tey, who reigned for few months before returning the throne to him.^[3]

In 1688,Dương Ngạn Địch, a Chinese adventurer and also a general of Nguyễn lord, was murdered byHoàng Tiến (黃進). Hoàng Tiến occupiedMỹ Tho and revolted against Nguyễn lord. Hoàng Tiến also attacked Cambodia. Using this excuse, Chey Chettha IV started to building fortifications and did not pay tribute to Nguyễn lord. In the same year the rebellion was put down, Chey Chettha had to pay tribute like before.^[2]

Chey Chettha IV abdicated in favour of his nephewOutey I in 1695. In the next year Outey I died, Chey Chettha IV restored.

Nguyễn Hữu Cảnh was sent to Saigon by Nguyễn lord to expand his southern territory. It violated Cambodia's advantages; Chey Chettha IV tried to drive them out, however, he was defeated. In 1700, Vietnamese army captured Phnom Penh. The vice king (uparaja)Ang Em (Barom Ramadhipati) surrendered to Vietnamese, and ascended the throne. Chey Chettha IV surrendered in the next year, he was allowed to restore.^[2]

Chey Chettha IV abdicated in favour of his sonThommo Reachea III in 1702. Chey Chettha IV then married a daughter to the vice king Ang Em. But, Thommo Reachea III drove out Ang Em with the help ofAyutthaya Kingdom. Ang Em fled to Saigon, in there he was supported by Nguyễn lord. A Vietnamese army underNguyễn Cửu Vân (阮久雲) invaded Cambodia again. Thommo Reachea III fled to Ayutthaya Kingdom. Ang Em came back to Cambodia and lived inLongvek. Chey Chettha IV was installed as the king by Vietnamese. He abdicated in 1706, and Thommo Reachea III crowned the king again.^[2]

With the help of Ayutthaya Kingdom, Thommo Reachea III came back to Cambodia, and captured Longvek in 1714. A Vietnamese army underTrần Thượng Xuyên andNguyễn Cửu Phú (阮久富) was sent to Cambodia to help Ang Em. They besieged Longvek. Chey Chettha IV and Thommo Reachea III were forced to flee to Ayutthaya Kingdom.^[4][2]

• Phoeun Mak. « L'introduction de la Chronique royale du Cambodge du lettré Nong ». Dans :Bulletin de l'École française d'Extrême-Orient. Tome 67, 1980. p. 135-145
• Phoeun Mak, Dharma Po. « La deuxième intervention militaire vietnamienne au Cambodge (1673-1679)» dans:Bulletin de l'École française d'Extrême-Orient. Tome 77, 1988. p. 229-262.
• Phoen Mak, Dharma Po. « La troisième intervention vietnamienne au Cambodge (1679-1688) » Dans:Bulletin de l'École française d'Extrême-Orient. Tome 92, 2005. p. 339-381.
• Achille Dauphin-MeunierHistoire du Cambodge P.U.F Paris 1968.
• Anthony Stokvis,Manuel d'histoire, de généalogie et de chronologie de tous les États du globe, depuis les temps les plus reculés jusqu'à nos jours, préf. H. F. Wijnman,éditions BrillLeyde 1888, réédition 1966, Volume I Part1: Asie, chapitre XIV §.9 « Kambodge » Listes et tableau généalogique No. 34 p. 337-338.
• Peter Truhart,Regents of Nations, K.G Saur Munich, 1984-1988ISBN 359810491X, Art. « Kampuchea », p. 1732.