Complex sentence: The Omaha speak a Siouan language which is very similar to that spoken by the Ponca, who were once a part of the Omaha before splitting off into a separate tribe in the mid- 18th century.
Split into simpler sentences: The Omaha speak a Siouan language that is very similar to that spoken by the Ponca. The latter were part of the Omaha before splitting off into a separate tribe in the mid- 18th century.