India’s West coast and the Greco-Roman world trade are in the Periplus of the Erythraean. It’s manual script by an Egyptian-Greek merchant in AD first century. The Periplus tells us that there were two routes from the Mediterranean to the red sea. One of the routes started from the ports of what is now Israel & Lebanon and made its way overland via Petra to the Gulf of Aqaba. The alternative route for Roman merchants to red sea ran through the great port of Alexandria in Egypt.
Socotra to India
The traditional coastal route to India from Socotra was to head north to Oman. This coast was controlled by Persians at that time & only fish eaters lived here. Past the mouth of Persian Gulf sailors would hit the Makran coast ( west coast ). From here, the ships would sail more directly east towards the Indus delta. The Periplus confirms that Sindh & parts of Gujarat were controlled by the Sakas & Parthians at that time. Beyond the Indus, the text says that there was a large gulf that ran inland but was too shallow to be navigable. This is the Rann of Kutchh, by AD first century; it was no longer possible to sail across it as in Harappan times.