Complex sentence: The first Greek colony in the region was Marseille, which became one of the largest trading ports of mediterranean by the 4th century BCE with 6,000 inhabitants and was also the local hegemon, controlling various coastal Greek cities like Nice and Agde.
Split into simpler sentences: The first Greek colony in the region was Massalia, which became one of the largest trading ports of mediterranean by the 4th century BCE with 6,000 inhabitants. Massalia was also the local hegemon, controlling various coastal Greek cities like Nice and Agde.