Evidence of the inhalation of cannabis smoke can be found as far back as the 3rd millennium BC as indicated by charred cannabis seeds found in a ritual brazier at an ancient burial site in present day Romania. The most famous users of cannabis were the ancient Hindus of India and Nepal. The herb was called ganjika in Sanskrit (गांजा/গাঁজা ganja in modern Indic languages). The ancient drug soma, mentioned in the Vedas as a sacred intoxicating hallucinogen, was sometimes associated with cannabis.
http://en.wikipedia.org/wiki/Cannabis_(drug)