Cursorily explored by Ernst Herzfeld and a team from the University of Chicago in the first half of the 20th century, much of Sasanian Istakhr remains unexcavated.

[1] Its religious importance as a Zoroastrian center was signified as early as the 4th century BC during the reign of Achaemenid King Artaxerxes II (r. 404-358).

[5] According to the Iranologist Mary Boyce, the ruins of this temple probably belonged to the original Achaemenid building, which had been destroyed and pillaged by the invading Macedonians led by Alexander the Great (r. 336–323).

[1] The center of resistance appears to have been Istakhr, which with its surrounding hills provided better protection than the nearby former Achaemenid ceremonial capital of Persepolis.

[1][6] Sasan, the eponymous ancestor of the later Sasanian dynasty, hailed from Istakhr and originally served as the warden of the important Anahid fire-temple within the city.

[2][6][5] According to tradition, Sasan married a woman of the Bazrangi dynasty, who ruled in Istakhr as Parthian vassals in the early 3rd century.

[5] It appears that in the early Sasanian period, or perhaps a bit before that, the Zoroastrian iconoclastic movement had resulted in the cult-image of Anahid being replaced by a sacred fire.

[5] Boyce notes that given the high-ranking status of Kartir, the appointment of these posts signify that the sacred fires at Istakhr were held in very high regard.

[2] In 648/9, General Abdallah ibn Amir, governor of Basra, conducted another campaign which once again forced Istakhr to surrender after heavy fighting.

[2] It was the site of an important fortress, which in Islamic times, "as no doubt earlier", often functioned as the treasury of the rulers of the city.

[1] On 11 April 890, Saffarid ruler Amr ibn al-Layth (r. 879-901) defeated the Caliphal governor Musa Muflehi at Istakhr.

[2] The geographer Al-Maqdisi, writing some thirty years later, in 985, lauded the bridge over the river at Istakhr and its "fine park".

[5][2] However, according to the modern art historian Matthew Canepa, archaeological evidence shows that the mosque was built in the 7th century during Arab overlordship, and was, therefore, not a converted Sasanian temple.

[2] The region's cold climate created accumulations of snow at the top of the castle of Istakhr, which in turn melted into a cistern contained by a dam.

According to a contemporaneous source, the Buyid Abu Kalijar (r. 1024–1048) found enormous quantities of silver and costly gems stored in the castle when he ascended it with his son and a valuer.

According to Bivar, who bases his arguments on the writings of Ibn al-Athir, the treasury of Istakhr held the treasures of earlier dynasties.

Ibn al-Athir wrote that when Seljuq Sultan Alp Arslan (r. 1063-1072) conquered the castle of Istakhr in 1066/7, its governor handed him a valuable cup inscribed with the name of the mythical Iranian king Jamshid.

[1][2] In 1074, during Seljuq rule, a rebel named Fadluya had gained control over the province of Fars and had entrenched himself in Istakhr's castle.

[2] In the first half of the 20th century, Istakhr was cursorily explored by Ernst Herzfeld followed by a team from the University of Chicago led by Erich Schmidt.

[2][6] The most detailed account of the ruins of Istakhr predating the 20th century excavations was made by the French duo Eugène Flandin and Pascal Coste in late 1840.