The article you linked describes how the Ottomans exercised significant control over the Sharifate, including the nomination of the Sharif himself. That seems like a vassal relationship to me, so the name is appropriate, I'd say.
What exactly are you proposing? Tying it to the capital location in Mecca? If so, what should the generic Arab vassal name be?
Guys, what do you think about allowing units to heal a little (worth 1 turn of idling) when they pillage improvement. Small tweak of rules -- big impact on military tactics and added realism. Red and yellow units does not just indicate depleted ranks and wounded soldiers, they indicate units low on morale, supplies and all kinds of problems. Spoils of war do have an ability to strengthen fighters.
The basic principle that we must follow in directing the armies of the Republic is this: that they must feed themselves on war at the expense of the enemy territory. (c) Napoleon
After we got Kremlin Wonder increasing civilian MP by 1 Russian settlers outrun Cossacks. No other civ has so much space to walk as Russia, so it is not so crazy. In reality we will have very real life MP ratios: infantry will move twice faster than artillery and light cavalry 1.5 times faster than infantry.What? Werent the Strelts given 2 MP so they could move together with cavalry?
There really should be a way to conduct diplomacy with Independents. As it is, they're just like barbarians, except that they can make peace with you.
What about adding an Ambassador unit? Sending and using it on any independent city you are at peace with grants a chance of you getting OB with the said independent civ.