Complex sentence: A diverse group gathered for the land run that included Kansans, Texans, Missourians, Oklahomans, African-Americans, Swedes, Bohemians, Germans, and Russians.
Split into simpler sentences: A diverse group gathered for the land run. It included Kansans, Texans, Missourians, Oklahomans, African-Americans, Swedes, Bohemians, Germans, and Russians.