Ros Sothea was born in circa 1948 to Ros Bun (Khmer: រស់ ប៊ុន) and Nath Samien (Khmer: ណាត់ សាមៀន) in Battambang Province.Growing up relatively poor on a farm, Ros Sothea was the second youngest of five children; her older sister Ros Saboeut later became known as an activist.She displayed vocal talent as a toddler and grew up listening to early Cambodian pop singers like Mao Sareth and Chhoun Malay. Sothea's talent would remain relatively hidden until friends persuaded her to join a regional singing contest in 1963. After winning the contest she became widely known in her home province and was invited to join a musical troupe that regularly performed at Stung Khiev restaurant in Battambang; she also performed in a family band with her brother Serey.[3] It is believed that Im Song Seurm, a singer from the National Radio service, heard of Sothea's talents and invited her to Phnom Penh in 1967.