There are quite a lot of moving parts in this, and predicting how people respond to crisis on a societal level is...an inexact science at best. So at the end of the day, a lot of this will depend on what kind of story you're interested in telling, what kind of themes and message you want to highlight. You could have a theme of "people are dicks", with various feudal lords trying to take advantage of the turmoil to gain more wealth and power for themselves, lots of underhanded machinations covered over with strategic alliances and so forth. But on the flip side, you could go for a theme of "humankind is one big family", with the crisis causing rival factions to put their differences aside for the time being and band together to defend their home. Either approach can be considered realistic, looking at actual history.
Hmm... thinking about it, I might go for a two or threesided approach on that one. Sure most people would try to work together and be it out of sheer desperation, while some might try to still stay on top and some might even consider throwing their lot in with the enemy at worst.
Harder to write and set up, but definitely worth the effort in the long run.
As for how the humans will handle the outsider incursion, I would expect a lot of reliance on the divine powers. You're looking at a time when religion was a hugely dominant force in Europe. Even if it later comes to light that the divine powers are not necessarily 100% on man's side, they will (at least initially) be trusted and welcomed for assistance in repelling the infernal forces. When actual, visible demons are out there making trouble, and an angel pops up in a church and says "I'm here to smite some demons", people are going to be praising God and lining up to help. Even when developments indicating that the divine forces might not totally be aligned with humanity's own interests, there will likely be considerable resistance to believing that (at least within Christianity). Church authorities would likely dedicate a lot of effort to rationalizing or covering up evidence of disharmony between the ends of man and the ends of heaven. This might end up leading to schisms between those who believe heaven has forsaken them, and those who retain faith that the heavenly acts that harm human interests are simply God's mysterious ways (or even rightful punishment for human sin).
This is actually something that I hadn't taken into account in such depth. That's right there a LOT of trouble waiting to happen in a great many different ways.
The revival of old gods or even new ones, would add another interesting layer on top of all that. The possible schisms, especially if the heavenly forces bring out sword and fire to start cleansing in depth, would also hit Christendom especially hard. In other regions like India the gods would take precedence and there would almost no magic users available if push comes to shove.
Overall, I need to look closely at that and brush up on a few things.
And speaking of religion, it's worth thinking about how these developments would alter religious relations from real-world history, and how religion would affect the response to these events. You have the appearance of magic happening right around the start of the Islamic Golden Age, and one of your two magical hotspots appearing in Muslim territory. How are the European mages traveling to the Sahara going to interact with the Muslims there? Will it be a military endeavour, conquering that region from the Muslims, or will they integrate into the existing Islamic society? Are there tensions between the original Muslim inhabitants and the European immigrants? Given that the endpoint for this society is a matriarchal setup, I would imagine the Islamic influence is largely overthrown, which might leave some lasting tensions in that region. Perhaps the Islamic social dominance was supplanted by less strictly patriarchal standards introduced by the European immigrants. Said immigrants may very well be from a splinter sect off of orthodox Christianity, or even pagans, given their apparent devotion to magic.
At first I think, the immigrants will settle deep within the Sahara and build their first settlement near the center of that magical hotspot, trying to unravel it's mysteries.
There will be almost certainly conflicts with the established Berber and Tuareg clans/tribes wherever they want to settle. After all at first they need an oasis to establish their city, which WILL lead to conflict. This might end in bloodshed at worst or the wizards might be able to negotiate a settlement.
Over time they will absorb several tribes into their fledgling polity, while also accidentally unleashing the curse that forms so much of their society.
The fact that they are relatively spoken powerful wizards gives a lot of incentive for the tribes to play nice with them in the long term, because they can provide a LOT of nice stuff like water, food and other amenities. Doling those things and more out to be left alone in peace by the tribes or to trade on their behalf with the outside world would be a win-win for everybody. Especially early on there will be raids and sieges against the wizards. Throughout the various peace and other agreements the wizards gain men and women from the tribes either as a form of appeasement/insurance that the peace sticks or as good will for services rendered.
I think it is doubtful that they would adopt Islam per se, especially when they are a motley crew of christianity sects and pagans.
This goes doubly because the Tuareg, while Muslims, already practice a highly customized version of Islam.
The real problem might be forces, mainly Berber, outside of the deep Sahara that decide to conquer them when they hear of the mighty desert wizards and their riches. This goes doubly for any city that is established on the border of the desert. Any attacks on cities deep within the Sahara are doomed from the start. With most of the tribes benefiting from the presence of the wizards living among them it is also unlikely that the various tribes would try to conquer them. The fact that their cities also fortresses to keep out the sand and possible hostile forces lends further credence to the assumption that lethal force is not an option employed against them by the various tribes.
Politically they would be rather isolated, especially the more the females come to more and more power. Most of the surrounding realms wouldn't like to deal with them, especially because the Islamic view on sorcery is a bit more extreme and ends usually with the death of an accused caster.
The fact that the different Berber factions wouldn't look favourable at them, due to the wizards claiming precious territory and them being wizards, is another thing, but to add insult to injury the Tuareg are most likely either closely allied with Wizards OR went fully over to them over time.
Because I could see the appearance of magic causing some schisms within European Christendom. Christianity at the time was not especially concerned with witchcraft (that was more of a Renaissance preoccupation), but the appearance of bona fide supernatural powers would likely bring that issue to the forefront of debate. Especially since both laypeople and clergy display supernatural abilities, and the functioning of those abilities is conspicuously different. You might have revivals of old pagan traditions in these magical hotspots as a response to Church pressure against magic use, or perhaps schisms within the Church between those who condemn the practice of magic and those who condone it.
Even with magic getting a head start of 100 hundred years, the sheer amount of priests running around will ensure that there is a staggering amount of priests equipped with real divine power 100 hundred years after the first wizards started appearing. At that time there will already some things have happened, I'd reckon.
Surely the church will be split between accepting or condemning wizards. This might lead to an even earlier split between east and west IF both sides find a different majority oppinion among themselves, but not in the other.
Also, there is most certainly a revival of some pagan pantheos and keep in mind the norse gods are still alive and kickin'... so to speak.
When after 100 hundred years the first norse priests start appearing this will get REALLY interesting.
Not to mention that spellcaster will find a relative safe haven long before that, because the norse and many german tribes believed in magic anyway.
So passing as a shaman or a bona fide wizard shouldn't be to hard among those people if push comes to shove.
And if the wizard in question can also create magic weapons he is settled for sure.
There's also the matter of the East/West Schism. At the time you're setting the beginning of the outsider incursion, the Church was still united. Tensions between east and west were just beginning to finally build to a head, and historically the schism resulting in present day Catholic and Eastern Orthodox churches would not formally begin until about 50 years after the outsiders begin to appear. Would the outsider incursion defuse those tensions, prompting east and west to put aside their differences to unite against a clear common enemy? Or would they exacerbate them? Perhaps the Pope seizing on the events as justification for a power grab further incenses the eastern Patriarchs who are already unhappy with the papal power creep. Or perhaps, since the infernal forces begin appearing in western territory, the east sees this as a sign of the corruption in the western Church?
Here I would go with defusing the tension. Otherwise this might get to complex or rather fractured.
There will still be splinter factions in the church that have different goals in the long term.
The fey are kind of a wild card in all this. It largely comes down to how religious views pan out. Some faiths may view the fey as benign, welcome allies in the fight against the demons. Others might view them as sinister beings, basically just demons in disguise. These differing views will likely exacerbate tensions between different religious groups. "See, those heretics have thrown in their lot with the forest devils!"
Yeah, the fey will be of great help to those who accept their help/ally with them, but also paint a big target on those same factions for doing so.
Here I see the Sand Wizards accepting their help without even blinking, knowing that they sitting on a Ground Zero of Outsider activity and being choosy in that situation won't work.
The problem with them is that they can unconsciously change the fate of humanity if they turn accidentally parts of mankind into fey creatures and therefore make them immortal. That this is a self-propagating thing wouldn't help at all. Mind you, I take some stories where fae act benign as hosts and offer food in their realm to humans and those turn to fey... something the fey don't know and neither mankind.
That will be a nasty shock for anyone involved and lend credence to anyone who said they are nothing than devils.
And that is definitely a point that most religions won't like or probably might also actively fight.
As for the mythical beasts, their appearance likely wouldn't shock people too much. This was a time when the top scholars generally believed that they actually existed; it wouldn't be so much a matter of "holy crap, there's dragons now?" but rather more "holy crap, there's been a real boom in the dragon population lately". I'd expect a lot of efforts to domesticate mythical beasts for use in fighting the infernal forces. Though some (notably, dragons) would likely be viewed as monsters to be repelled at all costs, pretty much lumped in with the demons. Griffon riders, likely. Dragon riders, probably going to be viewed as evil marauders if they exist at all.
"holy crap, there's been a real boom in the dragon population lately", that line made my day.
You are spot on here, I think.
Also it will be rather akward talk when a father has to explain to his son where the scales on his body come from.
"What do you mean Gramps is a dragon?"
"Don't fret, at least you got body armor out of the deal, son."
In the end, will they be able to keep the outsiders at bay? Depends on the relative power of the outsiders versus the assets at man's disposal. And, in particular, whether a means can be found to seal outsiders away or kill them for good. With outsiders banished rather than dying and capable of returning through the same portals, while men remain mortal, that's a recipe for the defeat of humanity in the long run if it eventually becomes a war of attrition.
Good point. Overall the rank and file outsider can be rather easy disposed of, albeit in a one on one you need still to be a badass to pull it off.
The problem that they just join up with the rest of their buddies on the other hand is something that can't really be solved, because basically their numbers are limitless.
Even by imprisoning the leaders of the outsiders will only bring a brief reprieve, until said leader is replaced.
Closing the portals is doable for mages equipped to deal with that, but in the end there will be other portals open, so that it will be very hard to keep them bottled up.
Things get even worse for those in the crosshairs of the gods, because sooner rather than later their agents on earth will try to kick those they don't like.
This in turn means that at worst some factions have to fight the infernals and divine beings, not to mention that eventually the divine outsiders on their side might take umbrage and demand of them to fight back.
The one advantage they have compared to the outsiders is that those have at best limited inherent magical abilites, but not the flexible magic mankind sports.
That's at least something. Mankind has in the end to stand together or fall... rather unceremoniously at that, or might that be to bleak?
Overall, I'd think that enclaves of priests and their flocks hold out on the surface against the infernal hordes through the help of their gods or rather their intermediaries.
Those not counting on the help of the divine entities on the other hand will probably have to dig underground. Either going full underdark style or at least burrowing under their cities and keeping those safe with mighty wards so that burrowing or teleporting into the hearts of their cities is not possible for the outsiders.
So any thoughts?