The ancient Arabic historian al-Balāurī (d. 892) begins his chapter on the conquest of Armenia by a description of the political conditions of those regions in Sassanian times. According to the local historical tradition, obtained from inhabitants of several Armenian towns, there had been a time when the people of the Hazars in Southern Russia were making continuous raids over the Caucasus passes and penetrated Persia as far as al-Dīnawar in Media. The first king to take energetic measures against these raids was Kubā (Kawā, 488–531). One of his generals ravaged Arrān (Albania) between the Araxes and the Kura; then Kubā came himself and founded or, better, fortified in this region the towns of al-Baylakān, Bara'a, and Kabala. He erected also a wall of brick which extended from the country of Širwān in the east as far as the pass called Bāb al-Lān, the “Pass of the Alans”. His work was completed by his son Kisrā Anūširwān (usraw I, 531–579), who fortified farther to the north the towns of al-Šābirān and Maskat, and finally the very strong town of al-Bāb wa'1-Abwāb, on the site of the later Derbend.