|Government type||Absolute Monarchy|
Arabia can be formed by any Arabian nation. Forming Arabia as Nejd has less requirements than forming it as the other Arabian States. The others must be a great power and influence at least one of the other Arabian nations. Nejd does only have to invade Hedjaz, and does not need to be westernized nor be a great power. Arabia formed as Nejd will be more or less identical to modern day Saudi-Arabia.
If one decides to Form Arabia it will most likely result in many wars against the other Arabian countries and Ottoman Empire. Arabia has cores in all of the Arabian countries and therefore free restore order-casus belli, which is the easiest path to success. If one is westernized before the 1870s, it is in an ideal position to colonize Africa, but it suffers from low literacy.
In addition to the cores and CBs, Arabia also has more accepted cultures than most nations.
Guide to Arabia formed by Nejd
Arabia is still an uncivilized nation and still have lots of problems associated with Nejd and Hedjaz. It has low literacy, a small population and no army to speak of.
On the other hand, one now have reconquest casus bellis against all other Arabian states and The Ottoman Empire. It will give a lot of research points to put Arabia on the course to westernization.
The first viable target is Abu Dhabi. It has no allies, and no army, so it is more or less a question of just placing your troops and declaring victory.
Afterwards, one have to turn towards Oman and Yemen. Oman will often be attacked by Portugal, so if one can time the invasion, it might be an easy job. After one have acquired and rebuild the armies of Nejd, Hedjaz, Abu Dhabi and Oman, Yemen should pose no threat.
Usually there are none of these countries, which will have any allies.
Now it all depends on what the European Powers have decided to do. Algeria, Morocco and Tunis are often attacked and annexed by European powers. Tripoli is likewise often re-annexed by The Ottoman Empire. If that is the case, then there is not a lot Arabia can do. If not, they are good targets at this point.
At some point one have turn to Egypt. The Ottoman Empire usually attack them, so one can time the attack, and almost meet no resistance at all.
After those have been annexed, one can move on to Ethiopia, Sokoto or Sindh until Arabia is ready to Westernize. Then one have to face The Ottoman Empire for Iraq and what they have taken of Eqypt and Tripoli.