Complex sentence: When Lewis and Clark visited Tonwantongo in 1804, most of the inhabitants were gone on a buffalo hunt, and they ended up meeting with the Oto Indians instead; however they were led to Chief Blackbird's gravesite before they continued on their expedition west.
Split into simpler sentences: When Lewis and Clark visited Tonwantongo in 1804, most of the inhabitants were gone on a buffalo hunt. They were led to Chief Blackbird's gravesite before they continued on their expedition west.