Complex sentence: A number of Oliver Meeker's friends from Indianapolis joined the group, most likely before the party left Iowa, crossing the Missouri River at the small Mormon settlement of Kanesville (today Council Bluffs, Iowa).
Split into simpler sentences: A number of Oliver Meeker's friends from Indianapolis joined the group, most likely before the party left Iowa. They crossed the Missouri River at the small Mormon settlement of Kanesville (today Council Bluffs, Iowa).