He inherited from his father Anawrahta the Pagan Empire, the first ever unified kingdom of Burma (Myanmar) but proved an inexperienced ruler.
He viewed Kyansittha, his half-brother and general in the Pagan army who was extremely popular with the people, with suspicion.
Saw Lu ascended to the Pagan throne on 11 April 1077 after his father Anawrahta had died under mysterious circumstances.
[9] To run the Mon-speaking territories in the south, he appointed his trusted childhood friend Yamankan, an ethnic Mon.
To administer the upcountry, Saw Lu, at the urging of Primate Shin Arahan, reluctantly brought back Kyansittha, who had been sent to exile by Anawrahta for his affair with Manisanda.
However, Saw Lu soon had to banish Kyansittha again (this time to Dala near Yangon) because the latter renewed his affair with Manisanda.
As Yamankan romped about in joy at his victory, Saw Lu taunted him, "If you are so clever, why don't you rebel against me?
In late 1082, he sailed up the Irrawaddy river with his army, and took a position on an island a few miles below Pagan.
However, other chronicles (Hmannan and Yazawin Thit) say he reigned only for five years, followed by an interregnum that lasted till 1084—implying that the king died in 1083.