India's indigenous coinage is rich and varied, distinguished by regional, cultural and linguistics features and representing imperial and political associations. The class of coins that finds frequent mention in ancient Indian epigraphs and literary sources is the karsapana. Karsapana, also known as Purana or Dharna, are the punch-marked coins which were in circulation throughout ancient India. Many hoards of silver punch-marked coins have been located in sites all over the country. Its widespread availability suggests that it was a standard medium of exchange from about the 6th century BCE.