Zahir al-Din Karawi was the leader of the Sarbadars

Sarbadars

The Sarbadars were a mixture of religious dervishes and secular rulers that came to rule over part of western Khurasan in the midst of the disintegration of the Mongol Ilkhanate in the mid-14th century...

 of Sabzewar for a part of 1355/56.

Reign

Zahir al-Din was the nephew of Yahya Karawi

Yahya Karawi

Yahya Karawi was the leader of the Sarbadars of Sabzewar from around 1351 until his death.-Reign:Yahya, an aristocrat, came to power after the assassination of Khwaja Shams al-Din 'Ali in around 1351. He had been informed beforehand about the assassination plot, and afterwards protected Shams...

. After his uncle's murder in 1355 or 1356, the partisans of Wajih ad-Din Mas'ud

Wajih ad-Din Mas'ud

Wajih ad-Din Mas'ud was the leader of the Sarbadars of Sabzewar from 1338/1339 until his death. Under his rule, the Sarbadar state developed its characteristic dual nature as both a secular and radical Shi'i state.-Early Reign:...

 attempted to take control of the government and install Mas'ud's son Lutf Allah

Lutf Allah

Lutf Allah was the leader of the Sarbadars of Sabzewar from 1356 until his death.-Life:Lutf Allah was the son of Wajih ad-Din Mas'ud, the second leader of the Sarbadars, and was considered by Mas'ud's adherents to be his legitimate successor. By the reign of Yahya Karawi he had come of age and...

 as head of state. They were, however, dispersed by Haidar Qassib

Haidar Qassib

Haidar Qassāb was the head of the Sarbadars of Sabzewar from 1355/56 until his death.-Biography:A possible member of the artisan guild, Haidar Qassāb served in the government of Khwaja Shams al-Din 'Ali as a collector of urban craft and trade taxes...

, who then declared Zahir al-Din as ruler.

In the meantime, some of Lutf Allah's supporters had escaped from Sabzewar. Lutf Allah's atabeg

Atabeg

Atabeg, Atabek, or Atabey is a hereditary title of nobility of Turkic origin, indicating a governor of a nation or province who was subordinate to a monarch and charged with raising the crown prince...

 Nasr Allah soon rebelled in Esfarayen

Esfarayen

Esfarayen is a city in and the capital of Esfarayen County, North Khorasan Province in Iran. At the 2006 census its population was 51,321, in 13,376 families.Esfarayen is one of the focal points for residence of Aryan tribes after entering into Iran....

. Haidar Qassib encouraged Zahir al-Din to move against the rebels but his advice was ignored. He then deposed Zahir al-Din and took control of Sabzewar himself.