Erzerum is a mountainous region that lies between the inland Mylasa Sea and the Videssian Sea and is bordered to the north by Pardraya and by Makuran to the southwest and Vaspurakan and the Empire of Videssos to the southeast. All the known Erzrumi tribes mentioned above fought against the Yezda and were part of the Arshaum host that invaded Yezd. However, because the defenders singled them out for fighting, most left the host and returned to their homes except for the Yrmido and some other tribes.