I am also interested in the interaction between the various countries in the early period. Here are some notes that I had made:
In around 1050AD the ordination lineage in Sri Lanka was broken and King Anawrahta of Burma sent monks to Sri Lanka to re-establish the lineage. (does this mean the current Theravada lineage doesn't come from the Mahavihara?)
Sri Lanka was invaded and most of it ruled, from 1215 to 1236 CE, by King Magha of Kalinga (modern-day Orissa, East India). During this period, the Sri Lankan bhikshu sangha was severely weakened. With the defeat of King Magha, Theravada bhikshus from Kanchipuram, a Buddhist center within the weakened Chola Kingdom in present-day Tamilnadu, South India, were invited to Sri Lanka in 1236 CE to revive the bhikshu ordination lineage.
During the reign on King Parakramubahu IV 33 senior monks frm Chiang Mai and Cambodia and 6 monks from Arakan all under the leadership of the Elder Medhankara visited Sri Lanka and obtained the higher ordination under Vanaratana Mahasami of Karagala. On their return in 1430 they persuaded 2 Sinahalese monks to accompany them to act as preceptors. They conducted large numbers of higher ordination ceremonies in Northern Thailand and Laos
- Jayawickrama, N. A., 1991 “The Medieval History of Buddhism in Sri Lanka : From the Polonnaru Period to the Kotte Period.”, Journal of Pali and Buddhist Studies.
- http://www.berzinarchives.com/web/en/ar ... art_1.html
There are also some Ph.D thesis done on monastic history at UK universities which are downloadable from http://ethos.bl.uk