Ali ibn al-Athir
In early Russian sources, the Circassians are referred to as "Kasogi", whereas in medieval Arabic sources, "Kasogi" is written as "Jarkas" and "Jahārkas". The spelling "Charkas" may be an abbreviation of Persian "Chahār-kas" ("four people"), denoting four tribes. Though "Jahārkas" was used by Ibn Khaldun (died 1406) and Ali ibn al-Athir (died c. 1232/3), the Persian hypothesis remains uncertain.