Complex sentence: It was the southern terminus of the historic Natchez Trace, which provided many pilots of flatboats and keelboats a road back to their homes in the Ohio River Valley after unloading their cargo in the city.
Split into simpler sentences: It was the southern terminus of the historic Natchez Trace. This was used by many pilots of flatboats and keelboats to return north to their homes in the Ohio River Valley after unloading their cargo in the city.