The township of Khoram Shahr experiences extremely hot and humid weather, and the Port of Khoram Shahr (Bandar-e-Khoram Shahr), is located 994 km. from Tehran. In the 12th century AH, Khoram Shahr was nothing more than a small village, and it was only in the beginning of the 13th century that it changed into a reputed sea port. It was under interest due to its strategic position, and therefore suffered repeated foreign attacks. The Ottoman Empire in the year 1883 AD, Britain in the year 1857 AD, and finally Iraq in the year 1980, surrounded Khoram Shahr respectively. Discovery of oil in 19th century and proximity to the oil refinery factory of Abadan frequently added to its importance.
The old name of Khoram Shahr under the influence of the red color of the Karoon River was "Mohammarreh". During the imposed war of Iraq, this city suffered heavy damages and loss, besides being occupied by the enemy for a period of 575 days. Ultimately regaining its freedom on May 23, 1982.