Al-Qadisiyah Governorate is one of the governorates of Iraq. It is in the center-south of the country. The estimated population of the province is about a million and a half million people, according to the census of 2014. Its capital is Al Diwaniyah. Before 1976, it was part of the ad-Diwāniyah Governorate, along with al-Muthannā and Najaf. The province is named after the historical city of Al-Qādisiyah, the site of the Battle of al-Qādisiyah, where in 636 CE the Islamic Rashidun forces defeated the forces of the Sassanid Empire. The governorate is predominantly Shia Arab. It includes the Mesopotamian marsh of Hor Aldelmj.