Saw Oo's grandfather served as the governor of Mindon. His father Saw Lu would later become governor of Toungoo (Taungoo), a major vassal state.[1] Saw Oo had two sisters.[2]
Saw Oo's career began in 1420. King Minkhaung I of Ava appointed his father as governor of Toungoo, and Saw Oo as governor of Yanaung, a small town in central Burma.[1] In 1426, he sided with his father, now styled as Thinkhaya, who refused to submit to the new king of Ava, Mohnyin Thado. Thinkhaya declared himself king, and launched a rebellion backed by the Hanthawaddy kingdom.[3][4] Thinkhaya seized the five irrigated districts of the Yamethin region, located directly north of Toungoo.[3]
Chronicles do not specify Saw Oo's exact role during Thinkhaya's reign. When Thinkhaya died in 1435/36, although Saw Oo was the only son, his brother-in-law Uzana succeeded the Toungoo throne. Saw Oo appealed to the other brother-in-law, King Binnya Ran I of Hanthawaddy, to intervene. Less than a year after Uzana's accession, Ran arrived with an army, and installed Saw Oo as king.[2][5]
Saw Oo's reign as vassal king lasted about four years. During the dry season of 1440–1441, Ava forces attacked Toungoo. Saw Oo attempted to break the siege by personally leading the Toungoo forces on his war elephant. In the ensuing pitched battle, he was killed by the Ava Commander Yazathingyan.[6] Tarabya was subsequently appointed governor.[7]
