The situation in Yunnan is different then Xinjiang. The cannabis growing all over Yunnan is feral. The locals weren't using it to get high. It grew everywhere, including at the police station. People there were amused when visiting foreigners were picking the stuff and getting baked. Their 'eradication' program was highly unsuccessful, as most eradication programs of the feral stuff are. When there's millions of plants growing across the province eliminating the ones in the big city near the police station is a drop in the bucket.
The Yunnan strains have variable amounts of cannabinoids. Ranging from higher CBD to higher THC. Generally as you move towards the equator THC becomes more prevalent, as you move away from the equator CBD becomes more prevalent. This is why, despite not being selected for high THC, there are still high THC varieties in Yunnan.
Xinjiang is different because it has an ancient hashish tradition that's alive to this day. I wish I could find it, a couple years back a Chinese guy posted about how Xinjiang migrants in the eastern big cities. 'always have hashish'. I've heard this from other people as well. There's certainly been crackdowns that 'raise prices' but the government hasn't succeeded in eradication and I don't think it's tried that hard. No idea how the recent nonsense in Xinjiang has affected the hashish trade, probably not good, but I'd be surprised if the government is able to stop it.
All the Muslim regions of China have a hashish tradition. Manchuria too. To bring this back on topic, the Japanese were dealing hashish and opium out of Manchuria during their occupation. There's pockets of hashish culture across northern Asia, in Mongolia and parts of Russia as well.
