There is an ample evidence available in the ancient literatures which inform us about the maritime trade activities of Sindh in ancient times which has been confirmed by archaeological discoveries in Sindh as well as in other parts of the world. The physical setting of Sindh has played a vital role during ancient time in the progress of international trade and commerce, as Sindh lies on the route between the west and the extreme East of the world. The ports of Sindh occupy the strategic location in the Indian Ocean. Therefore, being an important entity of this Ocean, this region has been playing an active role in navigation and maritime trade since the time immemorial. Moreover, the contribution of river Indus would also be worth mentioning with regard to the significance of Sindh as a crucial trading centre of the region. This paper aims to discuss trade activities carried out by the people of ancient Sindh. The classical works of Skylax, Strabo’s Geography, Pliny the Elder’s Natural History, a un known Greek merchant’s Periplus of Erythracean Sea, Ptolemy’s Geography and many other classical writings has been utilized in this study which enlighten us that the cities of Mohen-jo-Daro and Barbaricon (Modern day Banmbhor) were the main port cities of Sindh. The local and international trade improved the financial stability of the cities which turned into full-size urban centres, evident from the archaeological sites of these cities.