structural:expansion, quality:correction
Religious reforms

In 1056, a Mon Theravada Buddhist monk named Shin Arahan made a fateful visit to Pagan, and converted its king Anawrahta to Theravada Buddhism from his native Ari Buddhism. The king had been dissatisfied with the enormous power of Ari monks over the people, and considered the monks, who ate evening meals, drank liquor, presided over animal sacrifices, and enjoyed a form of ius primae noctis, depraved. In Theravada Buddhism he found a substitute to break the power of the clergy.

From 1056 onwards, Anawrahta implemented a series of religious reforms throughout his kingdom. His reforms gained steam after his conquest of Thaton, which brought much needed scriptures and clergy from the vanquished kingdom. He broke the power of the Ari monks first by declaring that his court would no longer heed if people ceased to yield their children to the priests. Those who were in bondage of the priests gained freedom. Some of the monks simply disrobed or followed the new way. However, the majority of the monks who had wielded power for so long would not go away easily.

Anawrahta banished them in numbers; many of them fled to Popa Hill and the Shan Hills. He used traditional nat spirits to attract people to his new religion. Asked why he allowed the nats to be placed in Buddhist temples and pagodas, Anawrahta answered "Men will not come for the sake of new faith. Let them come for their old gods, and gradually they will be won over."

Urged on by Shin Arahan, Anawrahta tried to reform the very Theravada Buddhism he received from Thaton, which by most accounts, was in a state of decay, and increasingly influenced by Hinduism. (The Mon chronicles hint that Manuha was reprehensible for making a compromise with Hinduism. Shin Arahan left Thaton because he was unhappy with the decaying of Buddhism there.) He made Pagan a center of Theravada learning by inviting scholars from the Mon lands, Ceylon as well as from India where a dying Buddhism was being given a coup de grace by Hindu Forces. The scholarship helped revitalize a more orthodox form of Theravada Buddhism.

To be sure, his reforms could not and did not achieve everything overnight. The spread of Theravada Buddhism in Upper Burma was gradual; it took over three centuries. Its monastic system did not achieve widespread village level penetration in more remote areas until as late as the 19th century. Nor did the Aris die out. Their descendants, known as forest dwelling monks, remained a powerful force patronized by the royalty down to the Ava period in the 16th century. Likewise, the nat worship continued (down to the present day). Even the Theravada Buddhism of Anawrahta, Kyansittha and Manuha was one still strongly influenced by Hinduism when compared to later more orthodox (18th and 19th century) standards. Tantric, Saivite, and Vaishnava elements enjoyed greater elite influence than they would later do, reflecting both the relative immaturity of early Burmese literacy culture and its indiscriminate receptivity to non-Burman traditions. Indeed, even today's Burmese Buddhism contains many animist, Mahayana Buddhist and Hindu elements.

He was the first of the "Temple Builders" of Pagan. His chief monument was the Shwezigon Pagoda. The work began in 1059 but was still unfinished at his death 18 years later. He also built the Shwesandaw Pagoda south of Pagan to house the hair relics presented by Pegu. Farther afield, he built other pagodas such as Shweyinhmyaw, Shwegu and Shwezigon near Meiktila.