version recorded in Syriac is of particular importance because it was current in the Middle East during the time of the Quran's writing and is regarded as being closely related to the literary and linguistic origins of the story of Dhul-Qarnayn in the Quran. The Syriac Alexander legend, as it has survived, consists of six distinct manuscripts, including a Syriac Christian religious legend concerning Alexander in prose text called the Neṣḥānā d-Aleksandrōs, often referred to simply as the Syriac Legend or Syriac Christian Legend, and based on it, a sermon known as the metrical homily (mēmrā), or Alexander song or poem ascribed to the Syriac poet-theologian Jacob of Serugh (451–521 AD, also called Mar Jacob), which according to Reinink was actually composed around 629–636. A key manuscript witness is British Library Add. 25875 (copied 1708–1709), which is the oldest of the five that were known to E.A.W. Budge and used as the base text for his English translation. The Syriac Legend concentrates on Alexander's journey to the end of the World, where he constructs the Gates of Alexander to enclose the evil nations of Gog and Magog, while the Metrical Homily describes his journey to the Land of Darkness to discover the Water of Life (Fountain of Youth), as well as his enclosure of Gog and Magog. These legends concerning Alexander are remarkably similar to the story of Dhul-Qarnayn found in the Quran. The Syriac Legend has been generally dated to between 629 AD and 636 AD. There is evidence in the legend of "ex eventu knowledge of the Khazar invasion of Armenia in A.D. 629," which suggests that the legend must have been burdened with additions by a redactor sometime around 629 AD. The legend appears to have been composed as propaganda in support of Emperor Heraclius (575–641 AD) shortly after he defeated the Persians in the Byzantine-Sassanid War of 602–628. It is notable that this manuscript fails to mention the Islamic conquest of Jerusalem in 636 AD by Muhammad's (570–632 AD) successor, Caliph Umar (590–644 AD). This fact means that the legend might have been recorded before the "cataclysmic event"` that was the Muslim conquest of Syria and the resulting surrender of Jerusalem in November 636 AD. That the Byzantine–Arab Wars would have been referenced in the legend, had it been written after 636 AD, is supported by the fact that in 692 AD a Syriac Christian adaption