Tanning is a foreign word, transliterated from denim, referring to denim with twill weave and indigo dyeing, also known as denim. In other words, all jeans are made of denim.
Generally speaking, cowboys are no different from tannins. However, in denim terminology, ordinary denim is called jeans or sacks, and tannin is specific and can be called denim. Two conditions must be met: one is to weave with Gu Zhuo weave; Second, natural indigo dyeing.