Amalananda Ghosh was the first to identify similarities between a pre-Harappan culture and the mature Harappan culture. Mohenjodaro was discovered in 1922 by Rakhal Das Banerji, an officer of the Archaeological Survey of India. The vast mounds at Harappa were first reported by Charles Masson in 1826, and preliminary excavation was done by Daya Ram Sahni in 1921. Sir John Marshall oversaw the excavations of Harappa and Mohenjo-daro, two of the main cities that comprise the Indus Valley Civilisation.