The West Asian War had created a deep sentiment of brotherhood between the Arab peoples, and even some of their neighbours. Sectarian strife, ethnic conflict, European imperialism and the nascent threat of communist vanguardism made it painfully clear that a political union was necessary. The Hashemites met in Cairo, the most important city in their sphere of influence, and chose the deposed Hussein bin Ali, father of the Arab Revolt, to become King of the Arabs as Hussein I. Egypt, Jordan, Iraq and Syria became emirates under their previous monarchs, while Kurdistan and Lebanon remained as autonomous republics whose president of choice was equal to the sovereigns of the Hashemite emirates. Later, in the 1930s, Kuwait would gain independence by referendum, becoming its seventh realm. This union was made official on the 1st of January 1925 with the signing of the Treaty of Cairo, becoming known until its collapse as The United Arab Kingdom. One of the most important events of this period is the discovery of oil in Kirkuk, Kurdistan. Shortly after, many other oil reserves would be discovered throughout the UAK.
Throughout the 1930s, the United Arab Kingdom oversaw a cultural, economic and demographic boom in the Middle East, owed primarily to the surprising resilience of its political institutions against sectarian conflict, tribalism and religious discord. Undoubtedly the two most important of these institutions were the Hashemite dynasty and the Arab Regular Army, both of which had been the creators of the union itself. Public spending, which was wisely directed towards education, infrastructure, land development and industrial works, was primarily funded by the oil industry; after the communist takeover of Iran in 1932, the Anglo-Persian Oil Company (one of the world's leading oil exporters) moved whatever assets it had left to the UAK, which had formed an alliance with The German Empire, and was receiving enormous foreign investment from The Kingdom of Italy, another great power interested in its energy potential.
As such, the UAK became Europe's main source of oil. A number of pipelines were built leading into the ports in Basra, Palestine and the Nile Delta, where tankers shipped the valuable product across the world. One notably destination was Venice, where oil was sent into the Alpine Pipeline towards Bavaria. This pipeline was built by the German government in 1937, owing to the rising threat of war, during which Germany could potentially find itself blockaded. War did come, and the Alpine Pipeline proved its usefulness as the "lifeline of Germany".
But the Eurasian Axis was not ignorant to the strategic importance of the United Arab Kingdom. Were they to fall, the Stahlpakt would run out of oil within months, perhaps even weeks. With that in mind, a coalitional force of Soviet, Turkish, Iranian and Konratopian troops invaded West Asia in October 1940, thus beginning the West Asian Theatre of World War II.
By the end of the war, Allied forces had occupied the Iranian provinces of Khuzestan, Kermanshah, Kurdistan and Ilam, putting them under Hashemite occupation (de facto annexation). However, the relationship between the West and the Hashemite kingdom was heavily strained by the Palestine War in 1948, during which much of the western world supported the cause of Zioniam independence, a cause which was ultimately successful. Tensions once more boiled in 1952, as the western-backed Free Officer's Movement attempted a coup on Hashemite rule. The final straw was in 1956, when the UAK ordered the Suez Canal to be closed for German, French and British ships, all of which claimed that their previous agreements regarding canal movement rights exempted them of taxes, for which they invaded Egypt alongside The Republic of Zioniam, thus beginning the Suez Canal Crisis. This crisis was defused by The United States of America and The Union of Soviet Socialist Republics in a rare act of shared interests (primarily anti-colonialism), by forcing the participants to lay down their arms, but the damage had been done.
After 1956, the Hashemites were in rapid decline. Their competitor in the oil industry, The Caliphate of Sadati Arabia, was a much more competitive exporter, the West hated them for the Suez crisis, the East hated them for being staunchly anti-communist and much of the Islamic world hated them for upholding secular government while, supposedly, being an Islamic monarchy deriving its moral authority from the Prophet's bloodline. While the world was distracted by the Cuban Missile Crisis, Sadat ordered Operation Taqwa, the beginning of the end for the Hashemite realm.