Ottoman distraction cleared Spain’s path to unify Iberia

Evidence

Suddenly, in the 1580s, the way was open for Christian Spain to unify the whole Iberian Peninsula. The Turks, or rather the particular Moroccan prince they sponsored, had lost at the Battle of Alcazarquivir, and so their westward advance was halted. But more important in their Anatolian homeland itself, extreme instability on their northern frontier, engendered by the Safavid menace, indicated that it was prudent for them to desist from overseas adventures. And since Granada, the channel through which Ottoman aid for al-Andalus had hitherto passed, had been so conclusively eliminated after 1570, the Turks no longer had a functioning network of sympathizers within the Iberian Peninsula. — L. P. Harvey, Muslims in Spain, 1500 to 1614, 1576

Categorization

• XREF: Connects to the broader pattern of empires withdrawing from distant theaters when their home frontiers destabilize — echoes the Elizabethan/Spanish Armada dynamic of European power politics reading.
• QUESTION: What exactly was the Safavid pressure on the Ottoman northern frontier in the 1580s, and how decisive was it relative to the other factors?