Why is it called authentic medicine? What do you mean authentic? What is the source?

Authentic medicinal materials, also known as authentic medicinal materials, are special terms for high-quality pure medicinal materials, which refer to medicinal materials with suitable origin, excellent varieties, rich output, exquisite processing, outstanding curative effect and regional characteristics. In the Song Dynasty, Kou Zongxuan said in Materia Medica Yan Yi, "Anyone who uses drugs must choose a place to do it, so the drama of the medicine is justified."