They are believed to be of ritual significance and produced by early pastoral and agricultural communities by the burning of wood, dung and animal matter.
A scientific explanation was first attempted by T. J. Newbold who sent notes on Būdigunta, one of the largest such mounds, to James Prinsep who published it in the Journal of the Asiatic Society of Bengal in 1836.
Newbold also pointed to Buchanan Hamilton's notes on the Rajmahal hills where he had described calcareous remains that the locals referred to as asurhar or giant's bones.
Around the same time two amateur archaeologists dug a mound in Kupgal and found bones, pottery, stone axes and other artefacts.
Two staple millets Brachiaria ramosa and Setaria verticillata which are not common in modern cultivation were found in several sites while the commonest legumes were Vigna radiata and Macrotyloma uniflorum.