major port city under the Abbasids' rule. The city was then a commercial source of salt and woven mats. The siltation of the river delta forced the town further away from water; In the 14th century, however, Ibn Battutah described Abadan just as a small port in a flat salty plain. Politically, Abadan was often the subject of dispute between the nearby states. In 1847, Persia acquired it from the Ottoman Empire in which state Abadan has remained since. From the 17th century onward, the island of Abadan was part of the lands of the Arab Ka'ab (Bani Kaab) tribe. One section of the tribe, Mohaysen, had its headquarters at Mohammara (now Khorramshahr), until the removal of Shaikh Khaz'al Khan in 1924. It was not until the 20th century that rich oil fields were discovered in the area. On 16 July 1909, after secret negotiation with the British consul, Percy Cox, assisted by Arnold Wilson, and Sheik Khaz'al agreed to a rental agreement for the island, including Abadan. The Sheik continued to administer the island until 1924. The Anglo-Persian Oil Company built their first pipeline terminus oil refinery in Abadan, starting in 1909 and completing it in 1912, with oil flowing by August 1912 (see Abadan Refinery). Refinery throughput numbers rose from 33,000 tons in 1912–1913 to 4,338,000 tons in 1931. By 1938, it was the largest in the world. During World War II, Abadan was the site of brief combat between Iranian forces and British and Indian troops during the Anglo-Soviet invasion of Iran. Later, Abadan was a major logistics centre for Lend-Lease aircraft being sent to the Soviet Union by the United States. In 1951, Iran nationalised all oil properties and refining ground to a stop on the island. Rioting broke out in Abadan, after the government had decided to nationalise the oil facilities, and three British workers were killed. It was not until 1954 that a settlement was reached, which allowed a consortium of international oil companies to manage the production and refining on the island. That continued until 1973, when the NIOC took over all facilities. After the total nationalisation, Iran focused on supplying oil domestically and built a pipeline from Abadan to Tehran. Abadan was not a major cultural or religious centre, but it played an important role in the Islamic Revolution. On 19 August 1978, the anniversary of the US-backed coup d'état that had