Oolong tea is without contest the hardest tea to grow and process. The special varietal used have a low yield and are sensitive to pest and disease. The processing is long and unforgiving.
This is also the most diverse family of tea, going from light Baozhong to highly oxidized Oriental Beauty. Roasting is another dimension added to the tasting profile of oolong. Some oolongs can even be aged!
Many Oolongs types are tied to a varietal: Dancong from Fenghuang Mountain, Yancha from Wuyi Mountain, Tie Guan Yin from Anxi county...
A variety of oolong cultivars are grown in Yunnan. On the outskirts of Pu'er you can find Jin Xuan and Qing Xin varietals. A couple of taiwanese tea producers settled in Yunnan during the 1990s, they established the plantation and some of them still manage them to this day.