Complex sentence: Upon realising his dream of becoming a professional singer, he returned to Vietnam in 1999 and released his first album, Những Ngày Xưa Yêu Dấu, in 2001.
Split into simpler sentences: Upon realising his dream of becoming a professional singer, he returned to Vietnam in 1999. His first album, Những Ngày Xưa Yêu Dấu, was released in 2001.