Ahvaz or Ahwaz (both: äwäzˈ) [key], city (1991 pop. 724,653), SW Iran, on the Karun River. It is an oil center, a transportation hub, and an industrial city that has petrochemical, textile, and food-processing industries. An ancient city, Ahvaz was rebuilt (3d cent. A.D.) by Ardashir I, who named it Hormuzd-Ardashir. In the 4th cent. Ahvaz became the seat of a bishopric, and a large church was built there. It was an important Arab trading center in the 12th and 13th cent. but later declined. The discovery of oil nearby in the early 20th cent. restored the city to its former importance. The new part of Ahvaz, the administrative and industrial center, is on the right bank of the Karun, but the population still is concentrated in the old section on the left bank. Ahvaz is linked by road, rail, and oil pipeline to ports on the Persian Gulf.