Saudi Arabia, Final episode?

OK, I've got to be done with this series I'm doing. This is the most time I've ever spent on one country or region, and there are library books overdue at the moment.
Previous parts of the series: One, two, three, four and five.

The union of Muhammad ibn Saud, emir of Diriya, and Abd al-Wahhab, founder of Wahhabism, started rather curiously. When al-Wahhab landed in Diriya, he needed an army to spread his new faith to the surrounding areas. Ibn Saud, as it happened, needed to have a religious justification for the tax he wanted to impose, which was counter to sharia. The pairing was made, although Wahhab later convinced ibn Saud that the spoils from conquering neighboring tribes would more than make up for the taxes he would collect and ibn Saud ended the taxation plan. The residents became fond of Wahhab for this act.
This was in 1744. One of Wahhab's tenets was the need for jihad. Not for personal struggle, but as a holy war to defeat infidels, either by conversion or death. This played well in the Najd, where tribal custom was all about raiding and plundering, but never set well with the western mountains and the holy cities.
Let's make a long story short. Over the next hundred and fifty years, the Saudi state would expand and contract. The expansions were often met with resistance, as local tribes changed their minds and wanted more independence. They got allies, but also had lots of enemies, notably the Shiites in the east, who hated Wahhabism with a passion. The Saudi kings were hereditary, but brothers and cousins often fought for control of the empire. Despite all this, there were times when there was stability like the tribes of the Najd had never known. Despite blood feuds, tribes often camped next to each other without bloodshed.
The expansion and state ended in 1818, when Muhammad Ali, the Viceroy of Egypt for the Ottoman Empire, invaded the holy land and in a matter of years fought the Saudis and Wahhabists back to Diriya. The first Saudi state ended.
Despite the last Imam, or ruler, of Diriya, Abdallah ibn Saud, being beheaded in Egypt after Diriya fell, the supporters of the regime would continue to work on uniting the tribes of central Arabia, and created a second Saudi state. Diriya was destroyed, so the capital was moved to Riyadh. The second state of expansion ended in 1891, but the son of the last ruler of this state, Abd al-Aziz, or Ibn Saud as he was known to the outside world, would found the next.

The next chapter of this land is very interesting, and the book goes into great detail, however I don't have time for all that. Ibn Saud would partner with the British, as the Sauds hated the Ottomans, who were allied with Germany. Saud used the war to gain the rest of the country. Even the Hijaz, the mountainous areas holding the holy cities, were supposed to become their own country ruled by the Sharifs, and including Syria and Jordan. The British promised the Sharif just that. However, they turned on Sharif, and gave the entire west coast to Ibn Saud.

Ibn Saud is a very interesting character, and I encourage all to get to know this period better. It includes the adventures of Lawrence of Arabia, and after the war involves the discovery of oil and the invasion (if you can call it that) of western commerce in the form of oil companies.