Since ~1350: Vladimir-Suzdal and later Chernigov start to expand into the woodlands between Volga and Ural (the former) and the area between the triangle Ryazan-Volgograd-Samara (the latter). The Muslim or pagan people living there are converted by force and assimilated, or killed and displaced.
1375: In an alliance with Hungary, the Teutonic Order conquers the princedom of Halicz-Volhyn, which is divided between them. The Teutonic part is object of German immigration and germanization too, and later forms the province of Wolhynien. Some Volhynians flee to the princedom of Kiev, which gains in importance by their influx.
1380s: When steppe people leader Arik-Buqa drives the Kara-Kitai and other Siberian people west, they also harass the Volga area. Eastern Russian princes make Vsevolod V Yuryevich of Vladimir-Suzdal their leader, to fight them.
1381: The western and south-western states from Smolensk to Chernigov elect the most popular of them, prince Vladimir V Rostislavich of Kiev, their leader, seeking protection against the Teutonic Order, the Kumans and the Hungarians.
1383: The patriarch of Kiev crowns Vladimir V Czar of all Rus. The difference between the South / West and Vladimir-Suzdal that already was apparent becomes even more outspoken. Main reason: While the West had to deal mainly with the Teutonic Order (and Novgorod in addition with Sweden), and the South with the Kumans, who had to retreat from the arriving Kara-Kitai (who fled again before Arik-Buqa, it's complicated...), Vladimir and its allies looked more to the East, where the Volga Bulgarians and Hungarians are.
1388: Russian schism begins, when the metropolitan of Vladimir and the patriarch of Kiev excommunicate each other, driven by the Czar / Grand Prince of Vladimir respectively.
1394-96: Black Death sweeps through Southern Russian states.
1397: Western Russian states struck by Black Death.
1397-1401: Novgorod hit by Black Death.
1399-1402: Black Death reaches Vladimir-Suzdal and other eastern Russian states.
|Earlier in time:||Russian lands
|Later in time:|