The Sassanid Persian Empire (pronounced /ˈsæsənɪd/; also spelled Sasanid Empire, Sassanian Empire, or Sasanian Empire), known to its inhabitants as Ērānshahr and Ērān in Middle Persian and resulting in the New Persian terms Iranshahr and Iran, was the last pre-Islamic Persian Empire, ruled by the Sasanian Dynasty from AD 224 to AD 651. The Sassanid Empire, which succeeded the Parthian Empire, was recognized as one of the two main powers in Western Asia and Europe, alongside the Roman Empire and the Byzantine Empire, for a period of more than 400 years.

The Sassanid Empire was founded by Ardashir I, after the fall of the Arsacid Empire and the defeat of the last Arsacid king, Artabanus IV. During its existence, the Sassanid Empire encompassed all of today's Iraq, Iran, Afghanistan, eastern Syria, the Caucasus (Armenia, Georgia, Azerbaijan, and Dagestan), southwestern Central Asia, part of Turkey, certain coastal parts of the Arabian Peninsula, the Persian Gulf area, and areas of southwestern Pakistan. The native name for the Sassanid Empire in Middle Persian is Eran Shahr which means Aryan Empire. According to legend, the vexilloid of the Sassanid Empire was the Derafsh Kaviani. It was also hypothesized that the transition toward the Sassanid Empire represents the end of struggle of ethnic proto-Persians with their close migrant ethnic relatives, the Parthians, whose original homeland was in modern-day Central Asia.

Mani (in Middle Persian and Syriac Mānī, Greek Μάνης, Latin Manes; also Μανιχαίος, Latin Manichaeus, from Syriac ܡܐܢܝ ܚܝܐ Mānī ḥayyā "Living Mani", c. AD 216–276), of Iranian origin, of Jewish-Christian background , was the prophet and the founder of Manichaeism, a gnostic religion of Late Antiquity which was once widespread but is now extinct. Mani was born in or near Seleucia-Ctesiphon in Asuristan (Assyria), at the time still part of the Parthian Empire. Six of his major works were written in Syriac Aramaic and the seventh, dedicated to the king of the empire, Shapur I, was written in Middle Persian. He died in Gundeshapur, under the Sassanid Empire.

Until the 20th century, no reliable information on Mani's biography was known. Such medieval accounts as were known are either legendary or hagiographical, such as the account in Fihrist by Ibn al-Nadim, purportedly by al-Biruni, or were anti-Manichaean polemics, such as the 4th century Acta Archelai. Among these medieval accounts, Ibn al-Nadim's account of Mani's life and teachings is generally speaking the most reliable and exhaustive. Notable in this account is the near-complete absence of the "Third Ambassador", who is merely mentioned with the name bašīr, "messenger of good news", and the absence of the topos of "Mani the Painter" (which in other Islamic accounts almost completely replaces that of "the founder of a religion").