10,000 BC Hash is made in Taiwan. Hashish is also called "Charas".
2,700 BC Dried Marijuana found in a tomb in the Gobi Desert. This Marijuana had all the males killed, meaning it was being grown for its psychoactive effects. In Germany they have discovered that Cannabinoids can reverse brain degeneration, and promote neurogenesis (the birth of new brain cells, and new neural pathways being created). So this is the first evidence of Psychoactive use, but it was probably used before this burial ceremony had it preserved with a person. And whenever people started using it, they would have (over generations and generations) had kids that had more neural capability, in theory.