DBWI: The Christians retook Al-Andalus

As we all know, Al-Andalus is the only Muslim-majority state on the European continent (albeit with a sizable Christian minority, especially in the north), but what if the Christians were able to "retake" Al-Andalus? What PODs would be necessary for such a scenario? What would a Christian Iberian peninsula look like?
You would need very early POD before you can get Christian re-capture. Probably some post-Visigoth kingdom should survive and even then it would be extremely difficult. You should at least make al-Andalus very instable nation.
Hard to imagine a world where that happened...

Well. Al-Jadida* probably wouldn't be al-Jadida if it did. Someone else would have gotten it. Which would have made world history quite different.

OOC: * OTL Brazil.
Would this somehow reduce the European,Islamic wars? Thus improving relations and increasing trade and cross cultural & population exchange in the last one or two centuries? Or would the Christian expulsion of the Ottomans from the Balkans keep things at a hostile level?
I think you'll need a united Christian kingdom to do it, rather than the squabbling petty kingdoms of OTL. I'm not sure how Asturias divided itself, but maybe there's your POD. In any case, southern Andalus was always richer and more populated than the poor north. Maybe a Caroligian empire, or a later France declares a crusade? It would have taken several decades and I think they've would bled dry.

Of course a Christian Al-Andalus would mean an entirely different discovery and colonization of Atlantis* and maybe the Atlantean kingdoms there would have been richer than OTL without the overwhelming Andalusian trade and colonization policies.*

*The Americas (north and south)
*Implying that there was not a wholesale conquest of the Americas like OTL Spanish Empire.
So, what do you think would be good PODs for a Christian Iberia and why?
There's a little known people that lived in the conquest era between the borders of the modern Frankish Commonwealth and the easternmost part of the Cantabriyya Province of the modern Andalusian republic. These were the Basque, an ancient people that some linguists claim that have spoken a non-Indoeuropean language isolate. Sadly, their culture was destroyed by forced assimilation policies enacted in Francia and Al-Andalus.

Let's say that the Franks decide to keep their Hispanic Mark buffer states instead of annexing them. This would have butterflied many Franco-andalusian wars and made the Pyrinees less garrisoned. Now, have one petty Basque king invade the Cantabrian coast, a place of permanent turmoil and general headache for the early Andalusian emirs. This new Christian Basque kingdom would be protected by the mighty Cantabrian Ridge and be able to lauch attacks to the northern Iberian plateau. This realm should also have good relation with Francia and the Eastern Roman Empire, wait for the inevitable taifa period and declare a crusade to free the suffering Christians from the Moorish yoke. The new reduced Andalusian Emirate would lose much strength and would no longer be a formidable naval rival to the Romans, who might even snatch Sicily and Sardinia from them. The loss of naval supremacy would then make Provenzal piracy even worse for the Mediterranean regions of the Emirate, causing their trade-based economy to go down in a spiral. Now sprinkle some Berber revolts, increase persecution of Christians and Jews, uphold Arab supremacy and you might as well end up with a fully Christian Iberia by 1600 AD.
Well, it might have a huge impact on the Great Reformist War; with Catholic England-Francia marching into the HRE to gain the Rhine after the Reformed Erik of Scandinavia was elected Emperor. I mean, the alliance between Al-Andalus and the Holy German Empire is still around today against the Greater Arcadian Republican State; world history has been formed around it. Without a constantly hostile power on the Plantagenet's southern flank they might have gotten Germany as well as England and Francia!
The Christians need a military more than anything. Historically they had squabbling knights and could barely mount a few thousand of them at once. Al Andalus has its city militias, its slave soldiers, its allied Berber tribes, its mercenaries coming everywhere from Senegal to Persia, and later on its professional army all under unified regional command.

However united the Christians were, the South is still a fortress.
I think Christians should have used the classical weakness of all states of that time - fragmentation. In addition, Islamic dynasties are extremely unstable. In many ways, Anadlussia existed for a long time as an appendage of the Moors.