31°45′N 44°08′E Al-Qādisiyyah (Arabic: القادسية) is a historical city in southern Mesopotamia, southwest of al-Hillah and al-Kūfah in Iraq. It is most famous as the site of the Battle of al-Qādisiyyah in c. 636, which saw a force of Arab-Muslim invaders defeat a larger army sent by the Sasanian Empire.

Prior to the Arab conquest, al-Qādisiyyah was but a small village on the western side of the Euphrates River, near an old castle at `Udhayb, and was possibly part of the Wall of the Arabs.^[1] However, during the centuries that followed, al-Qādisiyyah grew in size and importance and was a noted stop along very important highways of commerce that led to Baghdād and Mecca.^[2]

Al-Qādisiyyah was the scene of a decisive battle in the conquest of Persia by the Arabs around 636.^[3] The Muslim troops of the caliph `Omar led by Sa`d ibn Abī Waqqās despite their outnumbered forces defeated the army of the Sassanid emperor Yazdgard III, led by Rostam Farrokhzād. The battle of Al-Qādisiyyah would later be depicted in a manuscript of Shahnameh, a national epic authorized by the Persian poet Ferdowsi.

Another Qādisiyyah existed on the Tigris River, off the road between Baghdād and Sāmarrā', not very far from the Euphrates city. Both cities are recorded in the geographies of Ibn Khordadbeh.^[4]