It would have to be the Nubian kingdoms. Specifically Makuria and Alodia. Any Crusader entity that arises in Egypt would out of necessity, at least initially, with the local magnates to cooperate against the threat of migrating Saracen tribes who might use Nubia as a base to raid the north. In OTL, the Arabs did not overwhelm Nubia until the 14-15th century but the early collapse of Fatimid Egypt to the Franks may prompt an early migration southward.
As for Ethiopia, maybe something akin to the aborted attempt at a dual Aragonese-Ethiopian marriage alliance would occur between Jerusalem and Lalibela? Of course that's more long-term. The Crusaders would need to first succeed in conquering Egypt before any of what I mentioned can be speculated.
Yes, that's a good observation. I imagined that defeated Egyptians might make a run for the Red Sea instead of going south, considering the Nubians would be less than welcoming, but this indeed gives ideas for us to work regarding a possible "successor" Fatimid state lodged in between Upper Egypt and Makuria - even more as we work with the initial premise that the Crusaders, established in the Lower Egypt, will take some years to consolidate and initiate expeditions southward along the Nile Valley.
The Ethiopian contact is also something I intend to address in detail once we get there.
In actuality quite the opposite -- whereas Turkic peoples OTL achieved a massive range from Uighurstan to Pannonia, the Mongols only stayed cohesive as an ethnos as the Kalmyks and then in Mongolia itself, with the dynastic identity of Borjigin proving more important for culturally Turkic people like Timur. If they instead acted like the various Turkic peoples (and were, in turn, considered different but related groups in wider historiography), there would be more time to depopulate places like Transoxiana etc, and later invasions to replace and acculturate the surviving populations. In all likelihood, a "multi-Mongols" scenario lacks the sheer scale and speed of Genghis and his successors, but also provides a longer historical impact as a nomadic horde vis-a-vis OTL, where most of the Mongol age saw Mongol khanates acculturate to the conquered and create states. Its also definitely less coherent, because OTL divisions like the Oirats and Khamag would be further exacerbated by distance and time away from each other, and even further by the lack of a unifying Genghis Khan figure to instill a sense of unity and historical purpose in the Mongol tumens.
Excellent points. This is something I've never considered, indeed, but has a lot of potential. I suppose that their impact would be more perceived in Central Asia and in the Pontic Steppe, though, considering that their demographic base is relatively further in comparison to the Turkic peoples. I also imagine that the Mongols in any case would devote greater energy to establish themselves into the Far East than in Central Asia, but, in any case, you can be sure that we'll be returning to this point somewhere later.
Well, if Philip II can't have it and Aquitaine, then that just reverts the whole thing to the traditional royal policy, balancing the vassals.
Even though the crown and Aquitaine were usually on peaceful if not friendly term, I'd think that Phillip II could not allow to become his southern vassal to become too powerful by absorbing the County of Toulouse.
He already got the threat of a united Normandy-Anjou realm under the English King on the continent to deal with, and if he gets to deal with another such powerful vassal in the South, the Capetian monarchy would be reduced to the near powerless status it was at its beginning.
Unless of course you plan to butterfly either the death of William Adelin or the marriage of Mathilda with the Count of Anjou. That would keep Anglo-Norman and Anjou holdings apart, and though English Kings would still be a pain to deal with, at least Anjou would stay as a buffer between Normandy and Aquitaine, though that wouldn't remove Phillip II's need to avoid Aquitaine absorbing Toulouse.
All in all, what has been called as the Southern Hundred Years War risks to become all the more interesting ITTL.
Indeed. Phillip will most certainly continue his father's policy to expand the royal power and demesne at the expense of the great French magnates. Any debacle involving Aquitaine going into Provence will probably blow a powder keg, as weak as Royal France might appear to be, they will most certainly devote all their energy into preventing the formation of a mirror "Occitan" realm beyond the Loire.
I did not know the term "Southern Hundred Years War", that's a very interesting (even if symbolic) terminology that well represents the Occitan Medieval geopolitics.