The three main Roman ports involved with eastern trade were Arsinoe, Berenice and Myos Hormos. Arsinoe was one of the early trading centers but was soon overshadowed by the more easily accessible Myos Hormos and Berenice.

In India, the ports of Barbaricum (modern Karachi), Barygaza, Muziris and Arikamedu on the southern tip of India were the main centers of this trade.

Muziris is a lost port city in the South Indian state of Kerala which was a major center of trade with the Roman Empire.

Important pre-colonial ports of India included Barbaricum, Korkai, Muziris, Barygaza, Arikamedu, and Kaveripattinam.

St. Thomas, the apostle established the first Christian Churches in India in the mid-first century, from Wikipedia:

According to Indian Christian traditions, the apostle Thomas arrived in Kodungallur (also Muziris), Kerala, established the Seven Churches and evangelized in present day Kerala and Tamil Nadu.[17]

According to Catholic tradition, the Apostle reached Muziris, India in 52 AD and baptized several people who are today known as Saint Thomas Christians or Nasranis. After his murder and death by spear in India, the remaining relics of Saint Thomas the Apostle were enshrined as far as Mesopotamia in the 3rd century, and later moved to various places. In 1258 they were brought to Abruzzo, in Ortona, Italy, where they have been held in the Church of Saint Thomas the Apostle

One tradition, mentioned in the non-canonical Acts of Thomas, is that St Thomas was the apostle to India. Perhaps as a result of this writing, the indigenous church of Kerala has a tradition that St. Thomas sailed there to spread the Christian faith. He landed at the ancient port of Muziris then went to Palayoor, which was a Hindu priestly community at that time. He left Palayoor for the southern part of what is now Kerala State, where he established churches at Kodungallur, Kollam, Niranam, Nilackal (Chayal), Kokkamangalam, Kottakkayal (Paravoor), Palayoor (Chattukulangara) and Thiruvithancode Arappally.

Another tradition, mentioned by Origen in the third century is that Thomas was the apostle to the Parthians.

Neither of these traditions has any credible evidence to support it. We do not know where Thomas went.