Serious tea production in Yunnan after dynastic China happened only since WWII, when they homogeneously planted a couple of Assamica cultivars throughout tea plantations for the need to produce black tea for export to support the Resistance. Green tea tradition is shallow in that region, regardless of what myths and propagandas you might have read. Adding to that difficulty in developing better quality is the control of green collection price by a few major tea companies. They control distribution. This is very different from regions with strong green tea tradition where farms large and small all compete in an open market.
That is why Yunnan greens are still quite behind the rest of China in real quality output.
As for blacks, seems that you have gotten some lesser quality ones. Having said that, Yunnan blacks are not amongst the better blacks in China, regardless of price.
