wall, specifically the Caspian Gates of Derbent. An early expedition to Derbent was ordered by the Caliph Umar (586–644 AD) himself, during the Arab conquest of Armenia where they heard about Alexander's Wall in Derbent from the conquered Christian Armenians. Umar's expedition was recorded by the renowned exegetes of the Quran, Al-Tabarani (873–970 AD) and Ibn Kathir (1301–1373 AD), and by the Muslim geographer Yaqut al-Hamawi (1179–1229 AD): ... Umar sent ... in 22 A.H. [643 AD] ... an expedition to Derbent [Russia] ... `Abdur Rahman bin Rabi`ah [was appointed] as the chief of his vanguard. When 'Abdur Rehman entered Armenia, the ruler Shehrbaz surrendered without fighting. Then when `Abdur Rehman wanted to advance towards Derbent, Shehrbaz [ruler of Armenia] informed him that he had already gathered full information about the wall built by Dhul-Qarnain, through a man, who could supply all the necessary details ... Two hundred years later, the Abbasid Caliph Al-Wathiq (?–847 AD) dispatched an expedition to study the wall of Dhul-Qarnain in Derbent, Russia. The expedition was led by Sallam-ul-Tarjuman, whose observations were recorded by Yaqut al-Hamawi and by Ibn Kathir: ...this expedition reached ... the Caspian territory. From there they arrived at Derbent and saw the wall [of Dhul-Qarnayn]. The Muslim geographer Yaqut al-Hamawi further confirmed the same view in a number of places in his book on geography; for instance under the heading "Khazar" (Caspian) he writes: This territory adjoins the Wall of Dhul-Qarnain just behind Bab-ul-Abwab, which is also called Derbent. The Caliph Harun al-Rashid (763 – 809 AD) even spent some time living in Derbent. Not all Muslim travellers and scholars, however, associated Dhul-Qarnayn's wall with the Caspian Gates of Derbent. For example, the Muslim explorer Ibn Battuta (1304–1369 AD) travelled to China on order of the Sultan of Delhi, Muhammad bin Tughluq and he comments in his travel log that "Between it [the city of Zaitun in Fujian] and the rampart of Yajuj and Majuj [Gog and Magog] is sixty days' travel." The translator of the travel log notes that Ibn Battuta confused the Great Wall of China with that supposedly built by Dhul-Qarnayn. Gog and Magog In the Quran, it is none other than the Gog and Magog people whom Dhul-Qarnayn has enclosed behind a wall, preventing them from invading the Earth. In Islamic eschatology, before the Day of Judgement Gog and Magog will destroy this gate, allowing them to