According to Tamil inscriptions in Sri Lanka, we can get to know some information on trade relations between Sri Lanka and South India. In this study, the information on the trade relations between Sri Lanka and South India in the Tamil inscriptions found in Sri Lanka is studied investigative. This study was conducted under the research problem of, what information is contained in Sri Lankan Tamil inscriptions about the trade relationship between Sri Lanka and South India. And this aimed to obtain information on the economic connection between Sri Lanka and South India through Tamil inscriptions found in Sri Lanka. This whole research depends on the readings of Tamil inscriptions found in Sri Lanka. Hence, this could be categorized as desktop research and conducted as qualitative research. To collect data, I used library and museum studies under the secondary data collection method and later analyzed them. In this study, I got data from Tamil inscriptions found in the Anuradhapura, Kalutara, and Kurunegala districts and, the Sinhala inscription of Queen Lilawathi. Those inscriptions mention some South Indian trade corporations, that have been involved in foreign trade in Sri Lanka such as Ainnurruvar, and Nanadeshi. Weerakoti and Nanadeshi, which can be trusted as Ainnurruvar trade corporation and its affiliates, also appear to have been involved in foreign trade. The inscriptions state that the trading companies built and sponsored Buddhist and Hindu temples in the country. There were trade cities in Sri Lanka that were associated with trade corporations in Real-time and also tax collection was associated with those corporations. It can be concluded that during the Polonnaruwa period, South Indian trade corporations were active in Sri Lanka and Sri Lanka remained an economic hub.