Western Iberia from Galicia down to the Algarve is more Morisco than the rest of - well, we gotta call that "Spain". This is also concentrated in the men. Jacobo Pardo-Seco et al. verify this - but.
They affix the admixture to AD 620-70. The Arab-Berber invasion wouldn't happen until AD 711. What gives?
One possibility is that these were runaway Nafris. Deserters: who wouldn't fight the Sasanians then the Muslims but also disliked their change in status. From AH 20 / AD 640 on, "Islam" barely existed; the Arab invaders treated this as a cover for Umayyad / Syrian supremacy. As I keep reminding you, no written Qurân worthy of the name existed until 30/650. These people having the resources to leave slipped into west-Iberian societies as their elites. Many may have professed Judaism.
Alternatively, the admixture happened in north Africa in 620-70 and did not, at first, join the Iberians. It swamped the local population in the 710s without admixture. Clannish populations burrowed in and persisted.
