He defended his realm from the Umayyad Caliphate, who, under Yazid ibn al-Muhallab were defeated by Farrukhan, who laid ambush to his army.

He also spent much of his reign fighting the Dabuyid nobility, in which he was successful, and Farrukhan died in 728 with his son Dadhburzmihr succeeding him.

According to both Ibn Isfandiyar and Mar'ashi, the Dabuyids were descendants of the royal Sasanian family, tracing their descent back to Jamasp.

[1] According to the traditional account, the Dabuyids had established themselves as the autonomous rulers of Tabaristan in the 640s, during the tumults of the Muslim conquest of Persia and the collapse of the Sasanian Empire.

[2][3] A more recent interpretation of the sources by P. Pourshariati, however, supports that Farrukhan the Great was the one who actually established the family's rule over Tabaristan, sometime in the 670s.

[5] Not much later, Farrukhan's Daylamite subjects revolted against him, forcing him to flee to Amul, where he fortified himself in a castle named Firuz-Khusra.

The Daylamites, seeing the loaves, became discouraged on the thought of being able to starve out such a well provisioned place, and thus lifted their siege and withdrew to Daylam.

[7] In 716, the Arab governor of Iraq and Khurasan, Yazid ibn al-Muhallab invaded Tabaristan with the intent to conquer it.

[2] Regarding the founding of Saruyeh (modern-day Sari), Ibn Isfandiyar wrote that Farrukhan ordered a person named "Bav" to build a city in a rural place called "Ohar".

[13] The following rulers, Dadhburzmihr and Khurshid (r. 740–760) continued to mint the same pattern of coins, and eventually the Abbasid governors of Tabaristan.