As the Islamic State of Iraq and Syria (ISIS) sweeps across Iraq, taking over key regional towns and border crossings, asserting its control over Anbar Province, and even threatening Baghdad itself, Saudi has confronted the threat on its border directly. The establishment of a "caliphate" by ISIS, even if hardly anyone takes their claim to the title seriously, represents a direct challenge to the Al Saud, who themselves assert a religiously-based right right to rule. Even if ISIS has no meaningful influence or authority, beyond what they impose by force, the claim that the Ummah now owes allegiance to a "caliph" has practical consequences, both in terms of royal legitimacy, and political dissent within Saudi, and is seen as an usurpation.
Much has been written about how the export of Saudi ultra-conservative religious doctrine (referred to, erroneously but commonly, as "Wahhabism", after the 18th-century scholar Muhammad bin Abd al-Wahhab) influenced groups such as ISIS, whose theocratic ideology overlaps in many ways with the implementation of Islam so characteristic of the Kingdom. It has even been argued that this is a form of "blow-back", as when the creator loses control of his creation. There are interesting parallels, too, in the Kingdom's early history, when the zealous followers of Abd al-Wahhab joined forces with the Al Saud in a 1744 alliance, a mutually beneficial pact that survives to this day. The bedouin tribes, long accustomed to small-scale raiding and skirmishes, found religious justification for their predations in the teachings of the itinerant scholar., to which was now added the common cause of fighting under the banner of the Amir Muhammad bin Saud. Burning with zeal and ardor, motivated by a lust for plunder and glory, and totally unafraid of death, his armies were unstoppable, for this was "jihad", the legendary holy war to purge the world of corruption and sin, and the gates of paradise awaited them if they fell.
But there is another, less well-known but perhaps even more fascinating parallel. The Kingdom's founder, the Amir Abd al-Aziz, assembled a fighting force known as the Ikhwan, or "brotherhood" (no relation to the present-day Muslim Brotherhood), which he hoped to use as a spearhead in his decades-long campaign to bring the peninsula entirely under Al Saud control. Although the Ikhwan were fanatical warriors, the attempt at forming a religious army soon spiraled completely out of control. Organized in 1912, they were to be the crack soldiers of Allah and country, but within a few years had morphed into a murderous, lunatic horde. By the late1920s, they were beyond even the Amir's grasp, and he had no choice, ultimately, but to liquidate them in their entirety.
The Ikhwan were established in various settlements around central Arabia, where the young bedouin men were schooled in Wahhabi religious doctrine and taught the methods of desert warfare. During the World War, the new force did relatively little, as the territorial ambitions of the young Amir were tamped down by an informal alliance with the British, who preferred that he direct his attention to the Ottomans in the east, and away from their ally, the Hashemite dynasty, which controlled the Hijaz in the west. Abd al-Aziz' forces spent the war years consolidating his territory and engaging in minor frays with his main rival for power in the Najd, the al-Rashids of Ha'il, who he had ejected from Riyadh in a daring raid. In 1919, however, tensions with the Hashemites had come to a head, and the Sharif of Makkah sent a force to occupy a disputed area bordering the Hijaz.
It was not long before the Ikhwan arrived at the key town of Turabah. Fired with zeal, they were utterly merciless. Thousands were slain, and the carnage was such that Abd al-Aziz is said to have wept openly at the sight. The Sharif's forces had retreated, though the Ikhwan were forbidden from marching on Makkah in pursuit.