Complex sentence: After meeting in the woods, the two friends capture an Indian and learn that Custer has been killed at Battle of the Little Bighorn and that the Cheyenne are moving to join the Sioux Indians in the Black Hills.
Split into simpler sentences: After meeting in the woods, the two friends capture an Indian. From the Indian, they find out that Custer has been killed at Battle of the Little Bighorn and that the Cheyenne Indians are moving to meet up with the Sioux Indians in the Black Hills.