During the Hellenistic Era, Trade could be separated into domestic and international trade. Domestic trade was the one that happened into the same Hellenistic system, that was parts of the same kingdom despite their being different states.
International trade happened outside the limits of the Hellenistic world and went to India, Parthia, Arabic States, Italy, reached the Celts, the Scythians, and others.
Trade was done mostly by the sea - Mediterranean, Black Sea, Persian Gulf, and the Red Sea - and was very important for the economy even though it did not help to develop better ship technologies.