Ctesiphon was an ancient Iranian city, located on the eastern bank of the Tigris, and about 35 kilometres (22 mi) southeast of present-day Baghdad. Ctesiphon served as a royal capital of the Iranian empire in the Parthian and Sasanian eras for over eight hundred years. Ctesiphon was capital of the Sasanian Empire from 226–637 until the Muslim conquest of Persia in 651 AD.

Persian, also known by its endonym Farsi or Parsi, is a Western Iranian language belonging to the Iranian branch of the Indo-Iranian subdivision of the Indo-European languages. Persian is a pluricentric language predominantly spoken and used officially within Iran, Afghanistan, and Tajikistan in three mutually intelligible standard varieties, respectively Iranian Persian, Dari Persian, and Tajiki Persian. It is also spoken natively in the Tajik variety by a significant population within Uzbekistan, as well as within other regions with a Persianate history in the cultural sphere of Greater Iran. It is written officially within Iran and Afghanistan in the Persian alphabet, a derivative of the Arabic script, and within Tajikistan in the Tajik alphabet, a derivative of the Cyrillic script.