Why don't you pay attention? I never said Asturias or Cantabria or any substantial Berber settlement in the NW! After the Muslim invasion the Berbers were given garrison duty in Galicia, Castile-Leon and Basque Country/Navarre (they were protecting the northern frontier against attack by the Goths, Cantabrians, and Basques). They lived there for only 20-25 years with their families and then got fed up with the climate, constant attacks by Goths, maltreatment by the Arabs, and left to topple the Arabs. Of course the vast majority of the Berbers left with the three Berber Armies (one to conquer Merida and Cordova, another to take Toledo, and third to take Almeria). But many stayed, especially the mountain herders. They eventually converted to Christianity. They were not very numerous but if you imagine how the towns and cities were being repopulated at that time, the Berbers would have impacted on the DNA to a certain extent. The only big cities were Leon and Pamplona. So if you can imagine the race mixing that occured after the resettlement of Christians in the Duero Valley, then it would have added several percentage points to the Iberian DNA.
I know you have read some books that I am not aware of since its been almost two decades since I did my research but I do remember that the Berber population was 20% of the Muslim polpulation in Iberia. If we imagine 1/3 of the population was free of Muslim control and the 2/3 in Al-Andalus (and 80% converted to Islam), this will make 1.5-1.7 millions in the north and 2.5-3.3 millions in Al-Andalus if we use 4-5 million people during the 8th to 11th centuries. Thus the Berber population would have been about 500,000-660,000 in southern Iberia (southern Portugal, western Andalusia, and Valencia). Thus they would have impacted the Iberian DNA but to a limited extent (of course the Berbers were hated and looked down by European Muslims and Arabs as second-class citizens and the Berbers stuck to themselves and lived far apart from Europeans and Arabs, never the less they would have mixed to a certain extent. How much we don't know).