also spelled Sassanian, also called SASANID (ad 224-651), ancient Iranian dynasty evolved by Ardashir I in years of conquest, AD 208-224, and destroyed by the Arabs during the years 637-651. The dynasty was named after Sasan, an ancestor of Ardashir I.

Under the leadership of Ardashir I (reigned 224-241), the Sasanians overthrew the Parthians and created an empire that was constantly changing in size as it reacted to Rome and Byzantium to the west and to the Kushans and Hephthalites to the east. At the time of Shapur I (reigned AD 241-272), the empire stretched from Sogdiana and Iberia (Georgia) in the north to the Mazun region of Arabia in the south; in the east it extended to the Indus River and in the west to the upper Tigris and Euphrates river valleys.

A revival of Iranian nationalism took place under Sasanian rule. Zoroastrianism became the state religion, and at various times followers of other faiths suffered official persecution. The government was centralized, with provincial officials directly responsible to the throne, and roads, city building, and even agriculture were financed by the government.

Under the Sasanians Iranian art experienced a general renaissance. Architecture often took grandiose proportions, such as the palaces at Ctesiphon, Firuzabad, and Sarvestan. Perhaps the most characteristic and striking relics of Sasanian art are rock sculptures carved on abrupt limestone cliffs, for example at Shahpur (Bishapur), Naqsh-e Rostam, and Naqsh-e Rajab. Metalwork and gem engraving became highly sophisticated. Scholarship was encouraged by the state, and works from both the East and West were translated into Pahlavi, the language of the Sasanians.