By the efforts of his primate Shin Uttarajiva, the majority of the Burmese Buddhist monks realigned themselves with the Mahavihara school of Sri Lanka.
The future king was born to Prince Narathu and his wife (later known as Myauk Pyinthe, "Queen of the Northern Palace") in Pagan (Bagan) on 8 October 1150.
In 1171, his elder brother Naratheinkha succeeded the throne, the new king was greeted with multiple rebellions by the Kudus in the Tagaung region in the north and the Mons of Tenasserim coast in the south.
Following Anawratha's footsteps, Narapatisithu worked on increasing Upper Burma's economic and manpower advantages over the Irrawaddy valley.
His attempts to expand irrigation southwards into Minbu District by building a canal system repeatedly failed, and had to be abandoned.
[4] The Burmans, who had entered the Irrawaddy valley en masse only in the 9th and 10th centuries, had led the Pagan Kingdom under the name of the Pyu.
[5] Narapatisithu appointed Nadaungmya, great-grandson of Nyaung-U Hpi (one of the great Paladins during Anawrahta's reign), chief justice.
His chief minister was Ananda Thuriya, reportedly a man of valor who continually hunted down robbers and presented them alive to the king.
[10] According to the Pali Culawamsa Chronicles, the King of Polonnaruwa (Sri Lanka), Parakramabahu I, dispatched an expedition in 1180 to settle a trade dispute.
The Devanagala Rock Inscription of Parakramabahu I in Sri Lanka confirms the raid as it records donation of lands to a returning General from the victories in Ramanna (Burma).
On his deathbed, he placed the hands of his five sons on his chest and enjoined them to rule with mercy and justice, and to live together in brotherly love.