The conversion of the Volga Bulghars to Islam is commonly dated to the first decades of the 10th century, and by the middle of the 12th century, it is apparent that Islamic historical figures and Islamic forms of communal validation had become important factors for Bulghar communal and political cohesion. The Andalusian traveler Abū Hamid al-Gharnāti who visited Bulghar in the 1150s, noted that Iskandar Dhūl-Qarnayn passed through Bulghar, that is, the Volga-Kama region, on his way to build the iron walls that contained Yā'jūj and Mā'jūj and Magog within the land of darkness ... while Najib al-Hamadāni reports that the rulers of Bulghar claimed descent from Iskandar Dhūl-Qarnayn.