He began compiling material for his history in 1206, which up to then mainly consisted of the "Bavand-nameh", a now-lost work presumably in Persian which our author viewed as a Bavandid romance only.
On his return he stayed for two months in Rayy, where he came across in Rustam ibn Shahriyar's library the Uqidu sihr wa-qala'idu durar of Abu 'l-Hasan Muhammad al-Yazdadi - an Arabic history of Tabaristan subsequently lost.
[5] Ibn Isfandiyar translated this work into Persian, and this, coupled with genealogical and historical information on the Bavandids, formed the core of his history.
An anonymous later author continued it up to 1349, when the dynasty’s second period ended, based chiefly on Awliya Allah Amuli's Tarikh-i Ruyan.
Ibn Isfandiyar's work includes much unique historical, biographical and geographical information, including verses in Tabari language and a Persian translation of the Letter of Tansar, an important piece of Pahlavi literature, sent by the Sasanian ruler Ardashir I's chief priest to Gushnasp, prince of Tabaristan.