The two Shan states which arose from the ruin of Pagan, namely Panya (Vijayapura) and Sagaing (Jeyyapura), encouraged religion and learning. Their existence probably explains the claim made in Siamese inscriptions of about 1300 that the territory of Siam extended to Haṃsavatî or Pegu and this contact of Burma and Siam was of great importance for it must be the origin of Pali Buddhism in Siam which otherwise remains unexplained.
After the fall of the two Shan states in 1364, Ava (or Ratnapura) which was founded in the same year gradually became the religious centre of Upper Burma and remained so during several centuries. But it did not at first supersede older towns inasmuch as the loss of political independence did not always involve the destruction of monasteries. Buddhism also flourished in Pegu and the Talaing country where the vicissitudes of the northern kingdoms did not affect its fortunes.
Anawrata had transported the most eminent Theras of Thaton to Pagan and the old Talaing school probably suffered temporarily. Somewhat later we hear that the Sinhalese school was introduced into these regions by Sâriputta[155], who had been ordained at Pagan. About the same time two Theras of Martaban, preceptors of the Queen, visited Ceylon and on returning to their own land after being ordained at the Mahâvihâra considered themselves superior to other monks. But the old Burmese school continued to exist. Not much literature was produced in the south. Sâriputta was the author of a Dhammathat or code, the first of a long series of law books based upon Manu. Somewhat later Mahâyasa of Thaton (_c._ 1370) wrote several grammatical works.
The most prosperous period for Buddhism in Pegu was the reign of Dhammaceti, also called Râmâdhipati (1460-1491). He was not of the royal family, but a simple monk who helped a princess of Pegu to escape from the Burmese court where she was detained. In 1453 this princess became Queen of Pegu and Dhammaceti left his monastery to become her prime minister, son-in-law and ultimately her successor. But though he had returned to the world his heart was with the Church. He was renowned for his piety no less than for his magnificence and is known to modern scholars as the author of the Kalyani inscriptions[156], which assume the proportions of a treatise on ecclesiastical laws and history. Their chief purpose is to settle an intricate and highly technical question, namely the proper method of defining and consecrating a _sîmâ_. This word, which means literally _boundary_, signifies a plot of ground within which Uposatha meetings, ordinations and other ceremonies can take place. The expression occurs in the Vinaya Piṭaka[157], but the area there contemplated seems to be an ecclesiastical district within which the Bhikkhus were obliged to meet for Uposatha. The modern _sîmâ_ is much smaller[158], but more important since it is maintained that valid ordination can be conferred only within its limits. To Dhammaceti the question seemed momentous, for as he explains, there were in southern Burma six schools who would not meet for Uposatha. These were, first the Camboja[159] school (identical with the Arahanta school) who claimed spiritual descent from the missionaries sent by Asoka to Suvarṇabhûmi, and then five divisions of the Sinhalese school, namely the three founded by Chapaṭa's disciples as already related and two more founded by the theras of Martaban. Dhammaceti accordingly sent a mission to Ceylon charged to obtain an authoritative ruling as to the proper method of consecrating a _sîmâ_ and conferring ordination. On their return a locality known as the Kalyanisîmâ was consecrated in the manner prescribed by the Mahâvihâra and during three years all the Bhikkhus of Dhammaceti's kingdom were reordained there. The total number reached 15,666, and the king boasts that he had thus purified religion and made the school of the Mahâvihâra the only sect, all other distinctions being obliterated.