And so we happen to reach the vast East European Plains, the lands of the boreal taiga inhabited by the Uralic peoples, the deciduous forests of the Eastern Slavs and the Western Steppe of the Turkic peoples.
The westernmost people of the Steppe are the Pechenegs, having installed themselves between the lower Danube and the lower Dnieper, also include the lower reaches of the Dniester and the Prut. Even further, their realm would extend as far as the Don estuary in the east.
The Pechenegs have subjugated also a handful of Pontic Greek colonies located on the far shore of the Black Sea. Those settlements had also been one of the last refuges of the Marcionites, a very specific Gnostic community originating in northern Anatolia. On the other side, at the upper valleys of the Prut and Dniester, that is, in Upper Moldavia, were the domains of the Slavic tribes – Tivertsi and Uliches- who would be suzerain of the Pechenegs. The Pechenegs would have eventually allied with the Rhomaic Empire to raid the lands of the Khazars
The Crimean Peninsula remains as it was, populated mainly by Crimean Goths in the north and centre, and Greeks on the Pontic coast
The northern neighbours of the Pecheneg would be the Rus. This originally Varangian state would during the course of the 10th century be fully slavicized. The Rus realm would be greatly expanded during the 10th century, to encompass all the independent tribal realms of the East Slavs: to conquer the Pinsk marshes, Volhynia, Galicia up to the foothills of the Eastern Carpathians. In the east, the realm would incorporate the Oka river basin, the tribes of the Krivichi, Radimichi and the Meshchera.
One of the greatest rulers of the Rus was Sviatoslav I. the Brave, whose major feat was the defeat of the Khazars. Allying himself with the Pechenegs to counter superior Bolghar and Khazar cavalry, Sviatoslav eventually would conquer Sarkel and sack the Khazar capital of Atil. The Rus established outposts at Sarkel/Belaya Vezha and Tmutarakan – gaining full control of the Don trade route.
Sviatoslav would be followed by Yaropolk, who by turn would be succeeded by Vladimir I. (Vladimir Sviatoslavich, or Varangian: Valdemarr Sveinaldsson.
Sviatoslav of Kiev
Vladimir, during the first phase of his reign, would remain a (Slavic) pagan, taking up to eight hundred beautiful Slavic and Finnic concubines, erecting pagan shrines and temples. The Rus pantheon would include six major deities: Perun, the god of thunder and war , favoured by the Varangian elite; Slavic Stribog and Dazhbog; Mokosh worshipped by the Finnic peoples, and Khors and Simargl of Iranic origin.
However Vladimir sought to adopt ultimately some major world religion. Sending envoys all over the world to bring priests and scholars of all religious traditions, he soon dismissed the Manichean priests, for alcohol is the joy of his nobles and his subjects. His envoys were most impressed by the beauty of Rhomaic liturgy, claiming that they knew not whether they were in Heaven or Earth.
The Baptism of Rus goes on in a similar way as it happened well historically, and early Rus history goes in very much the almost same way as it would go in the world with a strict Arab monotheist religion.
Baptism of Vladimir
As for Khazaria, after Sviatoslavs campaign, Khazaria would be destroyed as a major power, despite retaining independence. It would be reduced to the region between the Terek and the Itil River, centered on some of the cities on the coast of the Khazar or Caspian Sea. The Circassian, Alan and Caucasian Avars would assert their own independence.
The Alans, an Iranian people dwelling on the northern foothills of the Caucasus Mountains, would ensure an alliance with the Rhomaic Empire, with their king adopting Christianity. His people, however, would accept this new religion relatively mildly, if at all.
Their western neighbours the Circassians, known to the Greeks as Kassogs would under Rhomaic influence accept Christianity. This conversion appears to be largely superficial and not fullhearted, as many of their tribesmen would remain pagan.
Beyond the lower Itil river was the emergent realm of the Cumans. The Cumans were a Kipchak Turkic people, with a strong Tengri religious tradition. They would hold the dog and wolf as a sacred animal. In fact, individual clans would be named after different types of dogs.
At the confluence of the Upper Volga and the Kama rivers would stand the realm of Bolgharia. Being a major trade centre, it would command fur trade from Permians going down the Kama River, while through the Volga River, Varangian merchants from Scandinavia and Merya would descend further southwards as far as Persia. Other trade partners would include local partners such as the Cheremis, the Mordvin but also the Yugrans beyond the Urals, Bjarmaland and Nenetsia along the Arctic Sea. The city of Bolghar would develop to a thriving city, rivalling even the city of Qtespon in Mesopotamia. Built of stone and brick, the city of Bolghar would thus have become the largest city on the Itil River.
Due to increased trade contacts with the Iranian plateau, the Bolghars would adopt Zoroastrianism from Persia. The high reverence of fire would in fact make very much sense in the continental climate of the Bolghar realm, especially during the severe winters.
The legend has it that the Bolgharian king was severely ill together with his wife. The local shamans and feltchers tried to cure him, but nothing helped, and the illness just worsened A Zoroastrian merchant, highly proficient in medicine happened to be present at the city of Bolghar itself. After hearing about this trouble, he agreed to help, on the condition that they accept his religion. They agreed and embrace the Religion of Fire.
After the defeat of Khazaria, Bolgharians would take over as the major power on the Volga River, monopolizing the trade on the Volga River.
While the Mordvins would remain an independent tribal people, in a periphery between the major powers of Rus, Bolgharia and Cumania, the Cheremis would not be able to hold onto their independence. They would be subjugated by the Merya, who had created a principality on the Upper Volga. This principality would act effectively as a buffer between Rus and Bolgharia. Ethnically Finnic, it would have come under the sphere of the Rus influence.
Ultimately we have the northern taigas. The area was populated by the Komi, the Vepsians, known to the Vikings as Bjarmians, and the Nenets. Out of these nations, only the Veps would have had considerable contact with the Vikings, to somehow change their society, mainly by incorporating them into the trade network of Eastern Europe.
(1) Historically, Volga Bulgaria would embrace Islam from Baghdad. However, their nearest trade partners would have been in Tabarestan, Iran. Other options would Nestorianism and Manicheism.