The Greeks cites did not keep separate when they came under the Roman Empire. They were all part of this empire and participated in the trade of this empire. Prior to Roman rule many Greek cities were independent city-states.
With thier colonies and other peoples and cities around the Mediterranean and Black Seas.
Greeks
they traded pizza and bread
they used big boats
They used the sea.
To establish new cities and for trade.
In pursuit of knowledge, trade and financial advantage.
Through agriculture, mining and trade.
they had a connection to the Aegean sea
they traded mostly food.
because they were poor and about to go out of food
They traded items that the have a surplus of for items that they cannot get.