Outey was the oldest son of Prince Outeyreachea (1707 - 1753) and Princess Peou, a daughter of King Ang Em, which made him heir to both rival branches of the Varman dynasty, since Outey's grandfather was King Ang Tong, who had ruled Cambodia.
When Outey was born in 1740, one year after the Vietnamese were expelled by the Siamese army, Chey Chettha's son King Thommo Reachea was ruling Cambodia for the third time in his life, until he died in 1747.
Thommo Reachea son and heir was murdered by a brother, the ministers chose a third brother as King, Ang Tong in 1748, but after being attacked by his relative Satha and a Vietnamese army, he fled to Siam.
During his exile, the people in Cambodia drove out the Vietnamese once again, and chose Chey Chettha V as King, who after ruling Cambodia for six years, died in 1755, when Outey's grandfather Ang Tong once again was elected King.
[citation needed] In return, Outey's elder brother Ang Tham was crowned as Maha Uparaja the title of heir apparent.