Complex sentence: In the 19th century, it separated the tribal domains of the Kalapuya and Umpqua tribes of Native Americans, both of which ceded their lands to the U.S. government in the 1854 Treaty with the Umpqua and Kalapuya.
Split into simpler sentences: In the 19th century, it separated the tribal domains of the Kalapuya and Umpqua tribes of Native Americans. Both ceded their lands to the U.S. government in the 1854 Treaty with the Umpqua and Kalapuya.