Yeah check our Clarke's "Hashish!" as he goes into some detail on this subject. From memory it's impossible to say, but cannabis and hashish practices seem to have started somewhere around Persia to Northern India but I remember Clarke speculating that there were probably parallel "discoveries" of cannabis and hashish extraction in the region. Certainly Afghanistan has the longest, modern hashish culture - but it was probably pioneered somewhere between Nepal and what is now a Western province of China (I forget the town's name but all of the best hashish makers were to be found there).