Supposedly the Scythians were into smoking weed, although I can't remember my source on that. It was some primary source I read as a freshman in college but I can't remember what now.
Herodotus, I think, mentions that Scythians (but as well Thracians and Dacians by their influence) used to fumigate hemp for religious purposes.
I don't really know why hashish didn't become more widespread in Europe but it certainly wasn't unknown at least in antiquity.
Because the hemp used in Europe was a different seed of Indian, having far less THC.
The sativa or indica seeds weren't cultivated past the steppes (and when I say cultivated, I mean Scythes planted some seed near camp grounds) or Middle-East.
The first mentions of a *recreative* usage of cannabis in Europe and Mediterranean basin are appearing only in the XII/XIII centuries after that Arabo-Muslims apparently not only made it widespread (probably with crossing it with different species and distillating the result) but forbade in the same row.
Before that, you do have a usage of european seeds in beverages, as beer, but it's always associated with other plants and less for the search of an 'effect" than taste or more prosaicly, "cheat" on houblon proportion.
You do have usage of cannabis that is or religious (as mentioned) or "energetic" (not unlike the coca in Andes), it's still really limited and efficiently rivaled by wine that was more customary and more present (probably cheaper to produce).