Alid dynasties of northern Iran or Alavids (Persian: علویون). In the 9th–14th centuries, the northern Iranian regions of Tabaristan, Daylam and Gilan, sandwiched between the Caspian Sea and the Alborz range, came under the rule of a number of Arab Alid dynasties, espousing the Zaydi branch of Shia Islam. The first and most powerful Zaydi emirate was established in Tabaristan in 864 and lasted until 928. It was interrupted by Samanid occupation in 900, but restored in 914 by another Alid branch. Local Zaydi rulers survived in Daylam and Gilan until the 16th century.