Buddhism first arrived in Sri Lanka in 249 BCE through the mission of the Indian Emperor Ashoka’s son, Mahinda. Although the date from which the name Theravada was used is in dispute, for the sake of simplicity we shall refer to this Buddhist lineage as "Theravada.” The Theravada bhikshuni ordination lineage was then transmitted to Sri Lanka in 240 BCE with the arrival of Emperor Ashoka’s daughter, Sanghamitta, to the island. By 1050 CE, this ordination lineage ended as a consequence of the Tamil invasion and subsequent rule of Sri Lanka under the Chola Empire.
from http://www.berzinarchives.com/web/en/ar ... art_1.html
Around 1070 the ordination lineage was reintroduced to Sri Lanka from Burma. After that it appears the lineage was broken and reintroduced many times back and forth between Sri Lanka and Burma and to a lessor extent Thailand.
Does this mean that the current Theravada Lineage does not trace itself back to the Mahavihara, but to that of Burma? Or is there evidence of an earlier transmission from Sri Lanka to Burma?