Complex sentence: In the 17th and 18th centuries, the company flourished from the North Atlantic triangular trade: trading with the Gold Coast of Africa for slaves, which in turn were traded for molasses and rum in the West Indies.
Split into simpler sentences: In the 17th and 18th centuries, the company flourished from the North Atlantic triangular traderoutes. Slaves from the Gold Coast of Africa were traded for molasses and rum in the West Indies.