Tyndis

Tyndis () was an ancient Indian seaport/harbor-town mentioned in the Graeco-Roman writings. According to the "Periplus of the Erythraean Sea," Tyndis was located north of port Muziris (Muchiri) in the country of the Keprobotos (present-day Kerala).
There are references to a port with the name Tondi, on the Kerala coast, in the early Tamil texts. It was under the control of the Chera rulers (probably via/under a collateral branch). No archaeological evidence has been found for Tyndis.
Sources.
Early Tamil texts.
There are references to a port with the name Tondi, on the Kerala coast, in the early Tamil texts. It was under the control of the Chera rulers (probably via/under a collateral branch). No archaeological evidence has been found for Tyndis.
Location.
The location of Muziris provides clues for the location Tyndis, which was 500 stades (92 km) north of it (by river and sea). 
In ancient times, Tyndis held close connections with Chera kingdom. The historic archives documented the Chera Kingdom as the powerful Tamil Kingdom whose turf extends the entire present-day state of Kerala, Kanyakumari and expanding up to Kongu Nadu.
The perfect array of religions, customs, languages, and traditions over the flow of time reflects in the prosperous heritage of Malabar. Upon reaching the Tyndis port, they further traveled to the inlands using smaller boats and then by carts to the hill stations of Wayanad or Coorg, and then on wards in search of spices and precious herbs.
The exact location of the port is still unknown. Possible candidates include the following modern locations: