Be that as it may, the inordinate report of Prester John’s magnificence became especially diffused from about the year 1165, when a letter full of the most extravagant details was circulated, which purported to have been addressed by this potentate to the Greek Emperor Manuel, the Roman Emperor Frederick, the Pope, and other Christian sovereigns.  By the circulation of this letter, glaring fiction as it is, the idea of this Christian Conqueror was planted deep in the mind of Europe, and twined itself round every rumour of revolution in further Asia.  Even when the din of the conquests of Chinghiz began to be audible in the West, he was invested with the character of a Christian King, and more or less confounded with the mysterious Prester John.

The first notice of a conquering Asiatic potentate so styled had been brought to Europe by the Syrian Bishop of Gabala (Jibal, south of Laodicea in Northern Syria), who came, in 1145, to lay various grievances before Pope Eugene III.  He reported that not long before a certain John, inhabiting the extreme East, king and Nestorian priest, and claiming descent from the Three Wise Kings, had made war on the Samiard Kings of the Medes and Persians, and had taken Ecbatana their capital.  He was then proceeding to the deliverance of Jerusalem, but was stopped by the Tigris, which he could not cross, and compelled by disease in his host to retire.

M. d’Avezac first showed to whom this account must apply, and the subject has more recently been set forth with great completeness and learning by Dr. Gustavus Oppert.  The conqueror in question was the founder of Kara Khitai, which existed as a great Empire in Asia during the last two-thirds of the 12th century.  This chief was a prince of the Khitan dynasty of Liao, who escaped with a body of followers from Northern China on the overthrow of that dynasty by the Kin or Niuchen about 1125.  He is called by the Chinese historians Yeliu Tashi; by Abulghazi, Nuzi Taigri Ili; and by Rashiduddin, Nushi (or Fushi) Taifu.  Being well received by the Uighurs and other tribes west of the Desert who had been subject to the Khitan Empire, he gathered an army and commenced a course of conquest which eventually extended over Eastern and Western Turkestan, including Khwarizm, which became tributary to him.  He took the title of Gurkhan, said to mean Universal or Suzerain Khan, and fixed at Bala Sagun, north of the Thian Shan, the capital of his Empire, which became known as Kara (Black) Khitai.[1] [The dynasty being named by the Chinese Si-Liao (Western Liao) lasted till it was destroyed in 1218.—­H.  C.] In 1141 he came to the aid of the King of Khwarizm against Sanjar the Seljukian sovereign of Persia (whence the Samiard of the Syrian Bishop), who had just taken Samarkand, and defeated that prince with great slaughter.  Though the Gurkhan himself is not described to have extended his conquests into Persia, the King of Khwarizm followed up the victory by an invasion of that country, in which he plundered the treasury and cities of Sanjar.