​   ​Archaeological excavations have shown that tashnau—hygiene corners—existed in medieval residential houses and production facilities. A tashnau consisted of a deep pit dug from the entrance room of the house, into which a large ceramic vessel with a drainage hole in the center was installed. The vessel was covered with tiles with a central drainage hole, creating a specially designated area for washing. After washing, wastewater flowed down through the system and was absorbed into the ground.              Although simple in design, this system played an important role in maintaining hygienic conditions in homes. Archaeological discoveries of such hygiene corners in every excavated residence in ancient Otyrar reflect the advanced urban culture of the medieval period.