What are the reasons for the absence of detailed leather craft in ancient literature?

Ancient literature does not have a detailed account of the leather craft, which may be: first, this craft is too old and disregarded. Second, in the feudal society has long existed in the concept of contempt for manual labor, belittling skills, and the leather craft is the traditional craft of the dirtiest, most tired one. Third, more importantly, when hemp, silk, cotton textiles after the introduction of limited raw materials, production process is complex, difficult, low yield leather products can only be in the clothing industry occupies a very secondary position.