Complex sentence: The Ahwahneechees were decimated by a disease in about 1800, and left the valley, although about 200 returned under the leadership of Tenaya, son of an Ahwahneechee chief.
Split into simpler sentences: The Ahwahneechees were decimated by a disease in about 1800, and the band left the valley. Approximately 200 returned under the leadership of Tenaya, son of an Ahwahneechee chief.