Some thoughts on the demographics of muslim western Europe.
As we can see, Iberia, southern Italy, mediterranean islands and french mediterranean coast have climate types (mediterraneans and semi arid) not too different from the Magrheb, and as in otl are quite likely to be prone to arab and berber colonization.
Regarding Al Andalus, I am gonna translate some things from the spanish wikipedia:
"The population of al-Andalus was very heterogeneous, especially at the beginning, and varied over time. From the ethnic point of view it was constituted mainly by Hispanogoths; followed by the Berbers, who made up the bulk of the Umayyad armies, the Arabs who were the dominant and leading group, other ethnic groups such as Slavs, Jews and a large mass of black slaves are also worth noting. From the religious point of view the population was either Muslim or dhimmi (Christians and Jews). The hispanogoths who had converted to Islam were known as Muladis, while those who preserved their Christian religion were called Mozarabic. Both groups adopted Muslim customs and ways of life. The ruling class was made up of Arabs, Berbers and Muladis and the dominated class was made up of Christians and Jews."
"Cities like Toledo, Merida, Valencia, Cordoba and Lisbon were important Mozarabic centers. Coexistence was not always conflict free. In Toledo, the Mozarabs came to lead a revolt against Arab rule. Some Mozarabs emigrated to the northern Christian kingdoms, spreading with them architectural, onomastic and toponymic elements of Mozarabic culture. The Jews were engaged in commerce and tax collection. They were also doctors, ambassadors and treasurers. The Jew Hasdai ibn Shaprut (915-970), became one of the trusted men of Caliph Abderraman III. As for its number, it is estimated that at the end of the fifteenth century there were about 50,000 Jews in Granada and about 100,000 in all of Islamic Iberia."
"It is very difficult to calculate the population of al-Andalus during the period of greatest extension of the Islamic domain (10th century), but a figure close to 10 million inhabitants has been suggested. The Arabs settled in the most fertile lands: the Guadalquivir Valley, Levante and the Ebro Valley. The Berbers occupied the mountainous areas, such as the Central Plateau and the Serranía de Ronda mountain ranges, being also numerous in Algarve, although , after the Berber revolt of 740, many returned to North Africa. In 741 a large number of Syrians arrived in al-Andalus with the aim of assisting in the repression of the Berber revolt, which would eventually settle in the eastern and southern peninsular. There are also sources that point to the presence of Yemeni families in cities like Silves. The presence of two minority ethnic groups, the blacks and the Slavs, is still worth mentioning."
The arabic settled regions mentioned there are this:
The Ebro river valley
The Spanish Levante (in red)
And the Guadalquivir river valley
And also the (Meceta Central) Central Plateu (berbers in this region will lickely arabized with the centuries, except those in regions too mountainous)
I expect that this regions will be mostly be arabized by the end of the middle ages thanks to constant migrations from the Maghreb and other parts of the arab world and also the prestige of the lenguage, and the populations will greatly increace with the
Arab Agricultural Revolution - Wikipedia . The arabs brought a lot of crops, technologies and techniques that were either new to the continent or were lost after the fall of Rome.
I suspect that mountain regions north and west will remain christian stronghold pretty much forever (like libanon and other mountain regions of the levant that remained full of minorities), and also strongholds of the latin based lenguages, which in ttl will keep more divided and the christian minorities in the south will tend to arabized (about the jews I am not shure, in otl their lenguage is latin based and really similar to castillian but without a christian resurgence they may arabized, OTOH the askenazi keep speacking german based yidish even after centuries of living under polish and slavic rulers so I am not shure). I guess that: galician, leonese and castillian will be restricted to the places they were used in otl XI century
, aragonese and catalan will be pushed away from the Ebro and towards the mountains by arab colonization and also convertion to islam, and basque will remain unbothered in their mountains (and quite likely christian, the different lenguage and complicated geography isolates them from muslim preachers). Although, I suspect that convertion of the elites will make urban spaces, even if surrended by overwhelmingly christian countryside, majority muslim in the long run.
For what I can tell, the italian mediterranean islands will go for a great degree of arabization, maybe even faster, thanks to the smaller population and territory, as it partially happened in otl "A similar process of Arabization and Islamization occurred in the
Emirate of Sicily (
as-Siqilliyyah),
Emirate of Crete (
al-Iqritish), and Malta (
al-Malta), albeit for a much shorter time span than al-Andalus. However, this resulted in the now defunct
Sicilian Arabic language to develop, from which the modern
Maltese language derives." I am surpriced that the Maltese pirates didnt take the chance during the Bizantine civil war to take Sicily or Crete.
It's interesting to note that the arab migrations in european territories were economically different than those in MENA, in the latter the arabs clans that migrated where mostly pastoralist and nomads, while in europe (as we saw in Andalus) they settled as agriculturalists bringing a green revolution. I guess that the pastoralist where unable to get all their animals on boats so they sticked to MENA and those that went to Al andalus wher more urbanised/settled.
Also another thing, aparently in the ttl territory of the kingdom of Asturias there used to be at this point still a lot of paganism, but that was solved by the migration of southern christians ruunig away from muslim rule towrds the last christian territory. If the Emir of Al andalus gets Asturias fast enough, there is the chance to convert those pagans to islam (like how in otl, the christian armenians where tolerated in the earlier caliphates but the pagan kurds where forced to convert to islam or pretend to be sabians).
Also how is Iberia faring without the Umayyads? According again to spanish wiki "After the rapid Muslim conquest of the Iberian Peninsula in the period 711–718, it was established as a dependent province of the Umayyad Caliphate. Its rulers set their capital in Cordoba and received the title of Valí or Emir from Damascus.
At that time the peninsular Muslim population was formed by the Arabs installed in the cities, the Berbers living in rural areas and the Syrians, who had formed the first invading forces. These ethnic groups confronted each other to gain the largest number of lands and plunged the peninsula into an endemic civil war until the appearance of Abderramán I." "In 750, the Abbasids overthrew the Umayyads of the Damascus Caliphate and ordered the murder of the entire Umayyad family. Six years later, in 756, Abderramán I - who had escaped the bloody final fate of the Umayyads fleeing Damascus - landed in al-Andalus and proclaimed himself emir (commander in chief) after conquering Córdoba and, in 773, became independent of the new capital Abbasí, Baghdad. This independence is political and administrative, but spiritual and moral unity is maintained by continuing the religious bond with the Abbasid Caliphate. Abderramán only ended up unifying Muslim Iberia in 781, after capturing Zaragoza (779) and Pamplona and having submitted to the Basque lords of the Pyrenees.
However, the true organizer of the independent emirate was Abderramán II, who delegated the powers in the hands of the visires and achieved a very rapid Islamization of the peninsula, considerably reducing the number of Christians in Muslim territory (called Mozarabic or dhimmis). However, these continued to represent the majority of al-Andalus at least until the eleventh century.
The disputes between Arabs and Berbers did not cease after the proclamation of the Emirate, which allowed the reorganization of the Christian kingdoms in the north, beginning the Reconquest, encouraged by the pro-Arab policy maintained by the Umayyad dynasty, which caused numerous uprisings starring by muladíes, who came to endanger the very existence of the Emirate.
Upon arrival at the throne of Abderramán III in 912, the political decline of the Emirate was an obvious and accomplished fact. To impose its authority and end the revolts and conflicts that ravaged the Iberian Peninsula, Caliph was proclaimed in 929 establishing the Caliphate of Cordoba."
So a dynasty of a lot of prestige was necesary to unify the muslim rulers of Iberia and avoid feudalization and fitna but at the same time the Umayyads contributed to future fitna with the same ethnic favoritism that caused the Abbasid revolution in the first place. I cant remember how the Berber revolt went in ttl. If it did go as in otl then the mhgreb will be a hotpot of religious sects and heterodoxy, with many types of shias and khawarijs going around. Thats why in otl the Fatimids started in Tunis.
Regarding south Italy (excluding islands) I guess that arab migration will be important but unlickely to ever become a majority, because i think that italy was in general better ruled (and thus more populated) fisrt by the romans and then by the byzantines while Hispania in comparation was kind of a backwater to the romans and later suffered the gothic invations which turned a really fertil region to pastoralism until the arab invation. Although there was a big orthodox greek population in the south before the italians assimilated them so we may get a souther italy dominated by three big ethnic groups. Of course with arabization I am talking really long term like a 1000 years or more, because in the early centuries the arabs will be a minority, but in continental italy and france I am not expecting them to become more then a majority only in some specific minor areas. Like the arabs from khuzestan and the iranian coast, they are lickely to lost space once latin speacking muslim states rice in a few centuries.
Regarding Faransa, I think they will experience something similar to the persian "two centuries of silence" regarding the political, cultural and social power of latin lenguages until the rise of a muslim dynasty of french origin.
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