The world’s first cannabis taxes were collected in 19th century India, so far as I know, and Dale Gieringer of California NORML, who is way ahead of me on this history, indicates that that is the case. This chart, from the 1894 Report of the Indian Hemp Drugs Commission, is for Bengal, and shows rupees (currency unit, plus subunits) per ser (about a kilogram), collected at wholesale. The Bengal model was followed generally elsewhere in British colonial India.
As in Colorado today with bud and trim, different cannabis products were taxed at different rates. http://digital.nls.uk/indiapapers/browse/pageturner.cfm?id=74574724
Thanks to the National Library of Scotland for posting this public domain material.