“Eastern” Xi Yang Qian (Rubia tirctorum L.) and “Western” Zhong Guo Qian (Rubia cordifolia L.): Across the Regions

Abstract Qian Cao (Radix et Rhizoma Rubiae) is a perennial grass with red and yellow pigments in its roots. It has been used since ancient times for fabric dyeing and painting, and it's the oldest red dye in both Europe and China. Xi Yang Qian (Rubia tirctorum L.) spread from the East to the West, while Zhong Guo Qian (Rubia cordifolia L.) spread from the West to the East. Both were integral in the development of Chinese and Western color cultures. Nowadays, although it is no longer commonly used in dyes and paints, Qian Cao is still used in clinical medicine as a medicinal herb.