English: Kalingapatnam was a major seaport in pre-11th century India, particularly active in the ancient times linking coastal Andhra and Odisha with southeast Asian ports. It and other sea ports helped the trade of goods as well as the spread of Buddhism and Hinduism to southeast Asia. Major Indian rivers were an important infrastructure in this trading network, and Kalingapatnam was the port on the mouth of Vamsadhara river. It was also a capital of the Kalinga empire.

After Asoka's violent conquest of Kalinga and by the 3rd-century CE, competing Buddhist schools had established many centers and monastic sites in Kalinga region. Three of these were along the Vamsadhara river – Dantapuram, Salihundam and Kalingapatnam.

Excavations at the Kalingapatnam site has uncovered a large stupa with 26 meter diameter, wiith a wheel shaped architecture similar to the one found in Nagarjunakonda along the Krishna river valley. The stupa has three concentric circles with spokes connecting them. At its center is a square hub. The site also has a smaller stupa (8 meter diameter), a Vedika and Ayaka platforms.

The archaeological excavations have also unearthed Vajrayana and Mahayana Buddhism-related items from southeast Asia and China of various periods, of which the most recent ones can be dated between 7th and 10th-century. This suggests that the Buddhist activity in Srikakulam district continued through the late 1st millennium CE.

The site's age can not be dated with certainty due to the lack of direct evidence such as early Brahmi inscriptions with chronological hints. However, the brick size and shape found in the Kalingapatnam stupa matches other Indian sites that can be dated with confidence to the 1st century CE. The Kalingapatnam site is therefore tentatively dated to sometime in or after the 1st century.