What is "qingdai"

Qingdai , a traditional Chinese medicine, is derived from dried leaves and stems of baphicacanthus cusia (Nees) Bremek., Polygonumtinctorium Ait., or Isatis indigotica Fort. Its main production is Zhejiang, Jiangsu, Anhui, Hebei and other places. The best quality of Qingdai is Fujian’s production, called “Jian Qingdai”. It is harvested and collected leaves of above said plants in fall, then immersed them into water to rotten, taken out the rotten leaves before added to a defined mount of lime milk, fully stirred immersion, and when the color of immersion changed from black green to deep red, taken out liquid foam and dried in the sun, finally, grinded powder.

Qingdai was first recorded in Yaoxinglun.