Jurchen

The Jurchens were an originally nomadic people people which considerably impacted the history of China over the past thousand years and more.

They originally lived in the northen part of what is now known as Manchuria and had a hunting-gathering culture typical of the Siberian-Manchurian tundra and coastal peoples. Like the Mongols and other such peoples, they took pride in feats of strength, horsemanship, archery, and hunting. They engaged in shamanic rituals and believed in a Supreme Sky Goddess.

Following a long period of increased Jurchen contact with Chinese and as well as Korean culture, the leader Wanyan Aguda 1115 unified the Jurchen tribes, declared himself Emperor, and proceeded to conquer a large part of China. His descendants, known in Chinese history as the Jin Dynasty, ruled until 1234 - when they were in turn overthrown by another wave of invaders from the north, the Mongols. During their century of rule over north and central China, the Jin Dynasty Jurchens were rapidly assimilated into the urban Chinese Confucian and Buddhist culture.

"Wild Jurchen" tribes which had not taken part in the Jin Dynasty invasion and had remained in the north and kept more of their traditonal way of life underwent a later Sinicization, at the time to the Ming Dynasty (1368 - 1644).

Finally, the Jurchen were transformed into the Manchus, who made another southwards invasion and ruled China between the 17th and 20th Centuries. Their descendants – by now assimilated in Chinese culture to the point of their original languague becoming virtually extinct – a still a major ethnic group in today's China.

Jurchens in Agent of Byzantium
The Jurchens were a nomadic people, originally from the far east, who in the 13th and 14th Centuries migrated westwards all the way to Europe, appearing in force on the steppes north of the Danube River where they displaced earlier tribes and posed a threat to the Byzantine Empire to its south.

The Byzantines did not know (and did not greatly care) what had driven the Jurchens from their original home and made them migrate so far west. What mattered was that they were a dynamic and capable people who presented an increasing threat to the Empire.

The Byazantines remembrered that there had been many earlier such nomadic invaders – Huns and Avars, Bulgars and Magyars, Pechenegs and Cumans - and that some of them did manage to breach the imperial borders and on occasion even threaten the capital Constantinople itself.

In the case of the Jurchens, moreover, not only were they courageous and skilled warriors, but their Shamans had some kind of magic enabling them to see over a distance, which gave a significant advantage in fighting the Imperial forces.

It was fortunate for the Empire that in the year Etos Kosmou 6814 (corresponding to 1305) its warrior Basil Argyros succeeded in discovering that this Jurchen secret was no magic, but a clever use of lenses which the Shamans put in front of each other inside a tube, enabling the holder to see distant things clearly at a distance. Argyros also managed to steal one such tube and bring it back to the Empire, to be duplicated.

This coup earned Argyros promotion to the elite corps of the magistrianoi, getting him embarked on his long and illustrious career as a spy and secret agent. Depriving the Jurchens of their monopoly of this remarkable invention made life easier for the Bynzantine forces on the Danube Frontier, though it by no means put an end to the Jurchen threat.

Literary Comment
The Point of Departure leading to the timeline of Agent of Byzantium is Muhammad's decision to convert to Chritianity rather than create a new religion. Turtledove does not explain in detail the chain of events leading from this to the Jurchens going all the way to Europe rather than invading China.

The link, evidently, has to do with the impact on China of Islam appearing in one timeline but not in another. In our timeline, Islam appeared to China's west as a dynamic new religion (and new empire) which was fast spreading in all directions. Though the Muslims never got so far east as to pose a direct threat to China itself, they were clearly a phenomenon which the Chinese needed to watch and which impacted China in various direct and indirect ways.

On the other hand, in the Agent of Byazntium timeline, what lay to China's west was the long-established Persian Empire with its long-established Zoroastrian religion, which had changed little over many centuries of existence and was in no mood for sudden moves. In such a situation, it might be conjectured that the Chinese could pay more attention to their northern frontier and be in a better position to repel invasions from that direction.