The new movement of commerce initiated by the conquest of Alexander
continued under his successors, though the break-up of the Macedonian
Empire in Asia in the 3rd century and the distractions of the Seleucid
court must have withheld many advantages from the Greek merchants which
a strong central government might have afforded them. It was along the
great trade-routes between India and the West that the main stream of
riches flowed then as in later centuries. One of these routes was by sea
to south-west Arabia (Yemen), and thence up the Red Sea to Alexandria.
This was the route controlled and developed by the Ptolemaïc kings.
Between Yemen and India the traffic till Roman times was mainly in the
hands of Arabians or Indians; between Alexandria and Yemen it was
carried by Greeks (Strabo ii. 118). The west coast of the Red Sea was
dotted with commercial stations of royal foundation from Arsinoë north
of Suez to Arsinoë in the south near the straits of Bab-el-Mandeb. From
Berenice on the Red Sea a land-route struck across to the Nile at
Coptos; this route the kings furnished with watering stations. That
there might also be a waterway between Alexandria and the Red Sea, they
cut a canal between the Delta and the northern Arsinoë. It was
Alexandria into which this stream of traffic poured and made it the
commercial metropolis of the world. We hear of direct diplomatic
intercourse between the courts of Alexandria and Pataliputra, i.e. Patna
(Plin. vi. § 58). An alternative route went from the Indian ports to the
Persian Gulf, and thence found the Mediterranean by caravan across
Arabia from the country of Gerrha to Gaza; and to control it was no
doubt a motive in the long struggle of the Ptolemaïc and Seleucid houses
for Palestine, as well as in the attempt of Antiochus III. to subjugate
the Gerrhaeans. Or from the Persian Gulf wares might be taken up the
Euphrates and carried across to Antioch; this route lay altogether in
the Seleucid sphere. With Iran Antioch was connected most directly by
the road which crossed the Euphrates at the Zeugma and went through
Edessa and Antioch-Nisibis to the Tigris. The trade from India which
went down the Oxus and then to the Caspian does not seem to have been
considerable (Tarn, _Journ. of Hell. Stud._ xxi. 10 seq.). From Antioch
to the Aegean the land high-road went across Asia Minor by the Cilician
Gates and the Phrygian Apamea.