The main focus of this study is the alliance between Abdul-Rahman Bin Marwan al-Julaiqi, the leader of Muladi of Gharb Al-Andalus, and Alfonso III of Austrias, the Christian and Spanish kingdom, during the reign of Muhammad Bin Abdul-Rahman Al-Awsat, and the consequences of the massacre against the Andalusian army at Al-Barbaria on the banks of river Orbigo inside the Christian territories in the year 263 H./877 A.D. The study examines the factors that took the Muladi, particularly in Gharb Al-Andalus, to revolt against the Umayyad emirate. The study also considers the factors that lead to the al-Barbaria tragedy, such as the rebellion by Al-Julaiqi against Cordoba, his alliance with the Spanish, his refuge to Austrias just before, and then his collaboration with the Christian armies who took the Muslim army by surprise. This lead to the slaughter of more ten thousand Muslim fighters and the other consequences, such as the catastrophe of the rest of the army in Valdemora, the official and public reaction to the consequences of the battle, and eventually the termination of al-Julaiqi revolution, and finally his settling in Badajoz.
Keywords: Abdul Rahman Al-Julaiqi; Gharb Al-Andalus; Muladis; Spaniards; Al-Barbaria.