Arab battles in Andalusia

The book "The Battles of the Arabs in Andalusia", by Boutros Al -Bustani, and this book talks beginning with the state of Andalusia, which was ruled by Muslims for nearly eight centuries, and they built palaces, civilizations and cities, and left all this civilization and all that its scholars wrote, and the Muslim Arabs contributed during their rule of Andalusia. In the enrichment and prosperity of European civilization, but the question that comes to mind, why did Andalusia fall? It is a question that surprises and surprised, but once the title is read "Andalusia''s battles", this surprise fades, as the author mentioned in his book all the battles that the West fought against Muslim Arabs for the sake of extracting Andalusia from them, and he mentioned it successively in which he presented the reasons that led to the weakness of Andalusia, and how it lost its unity and fell after it declared "Abu al -Hazm Jahr" who was the Minister of Andalusia and its disintegration to become twenty -two small states, so it became the way for the West Available to extract these states one by one, and Granada was the last of the states that fell from it, and this was in 1492, and the Muslims did not move any residents, and the Ottoman and Mamluk state played only the spectator, to drop the king of the Arabs, which was the source of Islamic civilization in the West.