They found it with the mummies when they went into the pyramids, the Chinese have documented its use for about 3000 years, rastafari's, mexico...
The only reason its used by fringe groups is because the us government waged an all out international war on a plant that grows naturally, spreading fear and propaganda across the globe. They pushed their will onto other countries and cultures and essentially told the world that if they didn't fall in line that they'd end up as an enemy of the USA. So, we ended up with what essentially amounted to a world wide ban, and the incarceration (or execution) of anyone who didn't follow their new rules.
It was probably the most widely used plant ever for not only its obvious recreational reasons, but medicinal, and fiber, fuel, etc.
Watch the film "Hemp for war" distributed by the us government, which forced farmers to grow it to aid in the war effort.
The first automobiles didn't run on gasoline or diesel, they ran on ethanol produced from hemp. Henry Ford had acres upon acres of the stuff.
Another interesting factoid. Anything that burns releases co2. Plants absorb co2 as they grow and release oxygen. Grow more than you burn, and you literally improve the air quality. Also, the problem we all have with petroleum based plastics was solved before petroleum based plastics were even invented. The model t had plastic panels, made from hemp, and they were 100% biodegradable. Only now do we see some plant based plastics popping up, and even then they're like 30% plant and 70% petroleum.
Did you know that the us government holds a patent on the use of (Staff removed) to treat a wide variety of ailments? Patent 6630507. They lie to us out of one side of their mouths, while simultaniously cornering the market out of the other.
I've done the research, honestly, and could literally go on for days.