The Periplus of the Erythraean Sea is a travelog written by an unknown author in the first century about travel in the Indian Ocean. According to K.A. Nilakanta Sastri in his book, A History of South India.
bq. The author of the _Periplus_ (c A.D. 75) gives the most valuable information about this trade between India and the Roman empire. He mentions the ports of Naura (Cannanore), Tyndis–the Tondi of the poems, identified with Ponnani–and Muziris (Musiri, Crangannore), and Nelcynda very near Kottayam, as of leading importance on the west coast. Muziris abounded in ships sent there with cargoes from Arabia and by the Greeks.
A Sreedhara Menon in his book, A Survey of Kerala History writes that there is no doubt that the present Kodungallor is the ancient Musiris. Now Dr. Shajan, an archeologist “has proposed”:http://www.hindu.com/lf/2004/03/28/stories/2004032800080200.htm based on some evidence that Muziris, the legendary seaport of the ancient world, stood at Pattanam, a small town some 12 km south of the Periyar rivermouth (present day Kodungallur)
bq. Radiocarbon dating of peat samples showed that Kodungalloor and Paravur areas were part of the sea some 5,000 years ago. By about 1,000 B.C., however, the sea had regressed and the coastline had more or less stabilised about two km west of the area where these two towns are situated at present. Another clue that led the team to Pattanam was the finding, based on remote-sensing data, that Periyar had changed course during the millennia, and the river course was in the Pattanam area 2,000 years ago. “My view is that the Paravur Thodu, which flows near Pattanam, was the old channel of the Periyar,” says Dr. Shajan.
bq. The most important find was the rim and handle of a classic Italian wine amphora, which came from Naples and belonged to the late first century B.C. The amphora, which was used to transport wine and olive oil, had been identified from a number of Roman sites in India, including Arikamedu and Alagankulam in Tamil Nadu. [via “The Hindu”:http://www.hindu.com/lf/2004/03/28/stories/2004032800080200.htm]