evidence: The Shatt al-Arab appears to have formed quite recently in the Earth's geologic time scale. Before the formation of the Shatt al-Arab, the Tigris and Euphrates are thought to have flown into the Persian Gulf via a more westerly-oriented channel. However, ever since its formation, the Shatt al-Arab has served as an important navigable route for the people settled along its banks. Since a long time ago, many have fought over the region containing modern-day Iran and Iraq, and especially constantly striven for control of the Shatt al-Arab territory. In 1935, as per the decision of an international commission, Iraq received complete control over the Shatt al-Arab territory, and Iran withheld the rights to maintain and manage only its Abadan and Khorramshahr ports along the river. This forced Iran to build alternative ports in the Persian Gulf. By the end of the 1970s, tension was high among the countries regarding the control of the Shatt al-Arab, and a full-fledged war broke out between them in 1980 as a result, and this conflict continued for eight years. The war involved a series of attacks from both sides on coastal areas along the Shatt al-Arab.