Hulegu (Hulagu) Khan (1217 – 8 February 1265), was a Mongol ruler who conquered much of Southwest Asia. Son of Tolui and the Kerait princess Sorghaghtani Beki, he was a grandson of Genghis Khan. Hulagu was friendly to Christianity, as his mother was a Nestorian Christian. Hulagu's army greatly expanded the southwestern portion of the Mongol Empire, founding the Ilkhanate of Persia, a precursor to the eventual Safavid dynasty, and then the modern state of Iran. Under Hulagu's leadership, the Mongols destroyed the greatest center of Islamic power, ####Baghdad, and also weakened Damascus, causing a shift of Islamic influence to the Mamluks in Cairo. It was also in Hulagu's reign that historians switched from writing in Arabic to writing in Persian. Hulagu's brother Mongke had been installed as Great Khan in 1251. In 1255, Mongke charged his brother Hulagu with leading a massive Mongol army to conquer or destroy the remaining Muslim states in southwestern Asia. Hulagu's campaign sought the subjugation of the Lurs, a people of southern Iran; the destruction of the Hashshashin sect; the submission or destruction of the Abbasid caliphate based in Baghdad; the submission or destruction of the Ayyubid states in Syria, based in Damascus; and finally, the submission or destruction of the Bahri Mamluk Sultanate of Egypt. Mongke ordered Hulagu to treat kindly those who submitted, and utterly destroy those who did not. Hulagu vigorously carried out the latter part of these instructions. Hulagu marched out with perhaps the largest Mongol army ever assembled – by order of Mongke, two in ten fighting men in the entire empire were gathered for Hulagu's army. He easily destroyed the Lurs, and his reputation so frightened the Assassins that they surrendered their impregnable fortress of Alamut to him without a fight. Hulagu's intent at that point was to continue south through Palestine towards Cairo to engage the Mamluks. However, Great Khan Mongke had died in late 1259, requiring Hulagu to return Karakorum to engage in the decision on who the next Great Khan would be. Hulagu Khan laid the foundations of the Ilkhanate State, and by doing so paved the way for the later Safavid dynastic state, and ultimately the modern country of Iran. Hulagu's conquests also opened Iran to both European influence from the west and Chinese influence from the east. This, combined with patronage from his successors, would develop Iran's distinctive excellence in architecture. Under Hulagu's dynasty, Iranian historians also moved from writing in Arabic, to writing in Persian.