Why wernt Muslims able to conquer most of Europe

Answer 1

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The Spanish occupation by the Moors began in 711 AD when an African army, under their leader Tariq ibn-Ziyad, crossed the Strait of Gibraltar from northern Africa and invaded the Iberian peninsula 'Andalus' (Spain under the Visigoths).
http://www.blackhistorystudies.com/resources/resources/15-facts-on-the-moors-in-spain/

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The Moorish Kingdom of Granada continued for three more centuries in southern Iberia. On January 2, 1492, the leader of the last Muslim stronghold in Granada surrendered to the armies of a recently united Christian Spain (after the marriage of Ferdinand II of Aragón and Isabella I of Castile, the Catholic Monarchs).
http://en.wikipedia.org/wiki/Moors