Complex sentence: The time frame of the migration is not precisely identified but is understood to be some time between the 10th century to the mid- 13th century, Alfough the arrival of the voyagers in Anuta could have occurred later.
Split into simpler sentences: The time frame of the migration is not precisely identified but is understood to be some time between the 10th century to the mid- 13th century. Alfhough the arrival of the voyagers in Anuta could have occurred later.