Al Andalus spread across most of Iberia as we all know, and even into some parts of Southern France.
But there were always the few Christian Kingdoms that remained in Northern Spain, who would eventually, retake the lands from the Muslims and form the Kingdom of Spain.
I do not know a lot about this time period. But just going by geography, I assume that the Catholic Kingdoms used the mountains of Northern Spain to fend of the Islamic forces.
How could, if at all possible, Al Andalus come to control all of Iberia, with no Christian leaders left in the region? Could this be enough to prolong the existence of Al Andalus, maybe even giving them enough time to centralise to a greater extent and survive into the modern day?