Complex sentence: With the arrival of white settlers from the East, the Indians began to depart and, by the turn of the 19th century, the last full-blooded Choctaw Indians left the area for land grants in Oklahoma.
Split into simpler sentences: With the arrival of white settlers from the East, the Indian tribes eventually left the area. By the turn of the 19th century, the last full-blooded Choctaw Indians left the area for land grants in Oklahoma.