The excavations of the archaeological site of Kosambi was done by G. R. Sharma of Allahabad University in 1949 and again in 1951–1956 after it was authorized by Sir Mortimer Wheeler in March 1948. Excavations have suggested that the site may have been occupied as early as the 12th century BCE. Its strategic geographical location helped it emerge as an important trading center. According to James Heitzman, a large rampart of piled mud was constructed in the 7th to 5th centuries BCE, and was subsequently strengthened by brick walls and bastions, with numerous towers, battlements, and gateways but according to archaeologist G. R. Sharma who led the archaeological excavation of the city, rampart was built and provided with brick revetment between 1025 BC and 955 BC and moat was excavated at the earliest between 855 and 815 BC. Carbon dating of charcoal and Northern Black Polished Ware have historically dated its continued occupation from 390 BC to 600 A.D.