In the 10th-century Persian "Shahnameh" ("Book of Kings") by Firdausi the term is used in the sense of "barley flour", but it's also used for a mixture of cracked wheat and cracked barley. Aubaile-Sallenave argues that the original Persian "kashk" known from early Persian literature was made with barley that contained either a mix of leaven with water or some fermented milk. To answer questions about the modern meaning in Iran for a dried dairy dish she argued "Iranian speaking pastorialists, for whom dried sour milk was a staple, and who had no easy access to barley, applied the word "kashk" by analogy to dry sour milk". Charles Perry offers an alternate explanation based on the 13th century Arabic cookbook "Wasf al-Atimah al-Mutadah" which says dried yogurt was a Turkomen style "kashk".