Isatis tinctoria L. (=Isatis indigotica F.) is a popular herb for indigo dye, medicinal uses, and cosmetics around the world. Along the legendary Silk Road linking China to Europe, indigenous people have a unique way of using I. tinctoria, eyebrow tinting. Especially in Uygur nationality, I. tinctoria is used for eyebrow tinting because they believe that this plant species can promote hair growth. In Uygur, the vernacular name of I. tinctoria is Osma, which means ‘the food of eyebrows’. To document this knowledge, we conducted four field studies from May 2019 to October 2022 in Xinjiang Uygur Autonomous Region, China and Khujand City, Tajikistan. We found I. tinctoria is not only used by the Uygur, but also by other nationalities (Tatar, Krigiz, Kazak, Uzbek, and Tajik nationalities) to promote hair growth. The fresh juices of I. tinctoria leaves and sticks made by I. tinctoria leaves were applied on the eyebrows, hairs, and eyelashes to promote hair growth. Moreover, our hair growth experiment further showed that indirubin was the active ingredient and it promoted hair growth by simultaneously regulating Wnt/β-catenin and TGF-β/Samd signaling pathways. Our results indicated that I. tinctoria is of great potential for the development of novel hair loss remedies.