Reishahr was a city in Fars province in ancient Sassanid Persia.

Located in the Arjan (ارجان) region, the city was also called Riu-Ardashir (ریو اردشیر).

The city is mentioned by many a historian, such as Farhang-i Anandraj, Hamdollah Mostowfi

Hamdollah Mostowfi

Hamdollah Mostowfi was a Persian historian, geographer and epic poet.Mostowfi is the author of Nozhat ol-Gholub , Zafar-Nameh , and the Tarikh e Gozideh . His tomb is a structure with a blue turquoise conical dome, at Qazvin.-References and notes:...

's Nuzhat-ul qolub, Majmal al-tawarikh

Majmal al-tawarikh

Mojmal al-Tawarikh wa al-Qasas was a book written in Persia in 1126 CE by an unknown author. The title means "The Collection of histories and Tales"....

, and Ibn Balkhi

Ibn Balkhi

Ibn Balkhi was a 12th century historian of Persia, in the city of Balkh, in present day Afghanistan.He is known for his work the Fars Nama . Dehkhoda dictionary mentions him to be a contemporary of Muhammad I of Great Seljuk....

's Farsnameh.

In particular, some historians such as Yaqut al-Hamawi

Yaqut al-Hamawi

Yāqūt ibn-'Abdullah al-Rūmī al-Hamawī) was an Islamic biographer and geographer renowned for his encyclopedic writings on the Muslim world. "al-Rumi" refers to his Greek descent; "al-Hamawi" means that he is from Hama, Syria, and ibn-Abdullah is a reference to his father's name, Abdullah...

's Mu'jam Al-Buldan

Mu'jam Al-Buldan

Mu'jam al-buldan is a book by Yaqut al-Hamawi, a Muslim scholar who is famous for his encyclopedic books.Al-Hamawi started the book in 1224 and finished in 1228, one year before he died....

 write of the city being centered around a pre-Islamic academic center of higher learning where scholars converged to study medicine as well as Indian and Greek sciences.

Dehkhoda dictionary

Dehkhoda Dictionary

The Dehkhoda Dictionary is the largest comprehensive Persian dictionary ever published, comprising 15 volumes . The complete work is an ongoing effort that entails over forty-five years of efforts by Dehkhoda and a cadre of other experts.The series initially consisted of 3 million records until...

 mentions that the city was eventually deserted and its inhabitants moved to Bushehr

Bushehr

Bushehr Bushehr lies in a vast plain running along the coastal region on the Persian Gulf coast of southwestern Iran. It is the chief seaport of the country and the administrative centre of its province. Its location is about south of Tehran. The local climate is hot and humid.The city...

.