Article: After defeating the Visigoths in only a few months, the Umayyad Caliphate started expanding rapidly in the peninsula. Beginning in 711, the land that is now Portugal became part of the vast Umayyad Caliphate's empire of Damascus, which stretched from the Indus river in the Indian sub-continent (now Pakistan) up to the South of France, until its collapse in 750. That year the west of the empire gained its independence under Abd-ar-Rahman I with the establishment of the Emirate of Córdoba. After almost two centuries, the Emirate became the Caliphate of Córdoba in 929, until its dissolution a century later in 1031 into no less than 23 small kingdoms, called Taifa kingdoms.

Now answer this question: Under whom did the Western part of Umayyad Caliphate's empire gain its independence?
Abd-ar-Rahman