Complex sentence: Billy Chinook was a member of the Wasco tribe and was a guide for John C. Frémont and Kit Carson who explored Central Oregon from 1843 to 1844.
Split into simpler sentences: Billy Chinook was a member of the Wasco Indian tribe. He was a guide for John C. Frémont; accompanied by Kit Carson, exploring the region of Central Oregon in 1843 to 1844.