The so called ' Kingdom of Prester John' was a Christian power thought to exist in Central Asia at the time of the twelfth-century crusades. At a deeper level for the steppe peoples it constitutes a distant dynamic which led to the world-shattering rise of Mongol power under Chinggis (Genghis) Khan. The book ranges widely in subject matter space & time. Christian history & ecological demographic social & economic history are all interwoven with the politics religions & literature of the vast & varied area between European Russia & China from c 800 to 1300. The author's views are distinctive & stimulating & are not always accepted by western specialists. But his bold synthesis fills in many of the missing links between histories of Europe & medieval China & makes it possible to think of these vast areas as in some senses parts of a greater whole.