The Dailamites were a people traditionally thought to have originated in the Alburz Mountains just south of the Caspian Sea, from where they launched several important military conquests in early Islamic times.
The Dailamites apparently were precursors of some of today's Kurdish populations, such as possibly the guran, nontribal farming peasants in the Sulaymaniya area of today's Iraq. In earlier times, however, the Dailamites apparently originated in the upper Tigris River area of Anatolia, possibly the home of their modern descendants the Dimili or Zaza Kurds. Most of the Dailamites were originally adherents of the Kurdish Cult of Angels religions with some Shiite influence. This may help to explain why the Dailamites were usually known for their religious tolerance of peoples they subjected.
Historic Dailamite dynasties included the Bavandis of the southern Caspian Sea area (665-1349), the Ziyarids of Tabaristan and Gurgan (927-1090), the Kangarids (also known as the Musafirids or Sallarids) of Azerbaijan (916-1090), the Jastanids of Gilan, Ruyan, and Talishan (c. 6th-12th centuries), the Shabankaras of Fars and Kirman, and the Kakuyids of central and southern Iran (1008-1119). The famous Buwayhid dynasty, which conquered Baghdad and the Abbasid caliphate in 945, was also of Dailamite origin. Daylaman in the Alburz Mountains was the site of the castle of Alamut, the legendary home of the Old Man of the Mountain. Alamut means "eagle's nest" in the Kurdish language of Dimili.
Historical Dictionary of the Kurds. Michael M. Gunter.