During the medieval period (10^th to 15^th centuries), South Indian merchants organized in guilds played an important role in the vigorous trade in the Indian Ocean connecting China in the East and Arabia in the West. There remain in India and Sri Lanka many inscriptions recording their activities and also a large number of sherds of Chinese ceramics brought from China attesting to their trade.

A team of Indian, Sri Lankan and Japanese scholars, which Prof. Karashima organized, has discovered many Chinese ceramic-sherds at Pandalayini-Kollam, Kollam, Kayal, Periyapattinam, and Motupalli on the Indian coast and Mantai in Sri Lanka. By showing the pictures of their ceramic-sherds and also by examining Tamil inscriptions and other literary sources, Prof. Karashima explained the maritime trade conducted in the Indian Ocean before the coming of Europeans.

Prof. Karashima is Professor of Indian Studies at Taisho University, and Professor Emeritus at the University of Tokyo. He was appointed President of the Epigraphical Society of India in 1985, and was also President of the Japan Association for South Asian Studies from 1996 to 2000. As the President of the International Association for Tamil Research, he organized in 1995 the Eighth International Conference-Seminar of Tamil Studies in Thanjavur. He was awarded the Japan Academy Prize in 2003 for his publication History and Society in South India: The Cholas to Vijaynagar, Oxford University Press, New Delhi, 2001.