After Nissankamalla's death, a series of dynastic disputes hastened the breakup of the kingdom of Polonnaruwa. Domestic instability characterized the ensuing period, and incursions by Chola and Pandyan invaders created greater turbulence, culminating in a devastating campaign by the Kalinga, an eastern Indian dynasty. When Magha, the Kalinga king, died in 1255, another period of instability began, marking the beginning of the abandonment of Polonnaruwa and the Sinhalese migration to the southwest from the northern dry zone. The next three kings after Magha ruled from rock fortresses to the west of Polonnaruwa. The last king to rule from Polonnaruwa was Parakramabahu III (1278- 93). The migration is one of the great unsolved puzzles of South Asian history and is of considerable interest to academics because of the parallel abandonment of dry-zone civilizations in modern Cambodia, northern Thailand, and Burma.
Data as of October 1988