Brunaburh
Gone Fishin'
so for hispania wed need to either avoid the arab conquest, or have the reconquest undertaken by one state. if moorish spain was left intact, would that create a hard language border?
I don't like the word reconquista, because the pre-Moorish population of northern Spain had never been in charge of the conquered territory. But, in the case of only one state conquering Iberia, it is likely to be *Leon or *Asturias, you would get a hard language border with a chain of dialects on the southern side of the Pyrenees. There would be *Navarro/Aragonese with its Basque influence inland and *Catalan on the coast, but as OTL, there would be no clear dividing line between the two. However, as in OTL, after a few hundred years you would get a narrow transitional zone between *Montanes and *Leones, assuming there was some factor protecting the mountain varieties from disappearing.
Moorish Spain left in tact seems to have been heading towards Arabisation. Linguistic evidence is difficult, but southern Valencian Moors were still Arabic-speaking in 1500, and I've seen no evidence of a Latin population in Granada.