Answer:
The main advantage was that they could dominate the trade across the whole Mediterranean, thus strengthening their influence and spreading Greek civilization.
Step-by-step explanation:
The Greek colonization was an organized process that lasted between 8th and 6th Century BC. It was started because of the over-population, but it had large consequences on the spreading of Greek influence in the Mediterranean.
Many colonies, which were source of colonies remained in close ties with their motherlands.