Complex sentence: He apparently inherited the chiefdom of about 4-6 tribes, with the base at the fall line near Richmond, and through diplomacy and/or force, had assembled a total of about 30 into the Powhatan Confederacy by the early 17th century.
Split into simpler sentences: He apparently inherited the chiefdom of about 4-6 tribes, with its base at the fall line near present-day Richmond. Through diplomacy and/or force, he had assembled a total of about 30 into the Powhatan Confederacy by the early 17th century.