Novorossiya (New Russia) was how the Russians from TTL called OTL Siberia. Since 1460, the Russian lands suffered from overpopulation: The Russian population had recovered from the Black Death (and due to a less densely settled population, a smaller part of the people had died than in Western Europe). Since the pressure of their feudal lords became harder and harder too, peasants started looking for land. So they settled in neighboring areas: Those from Novgorod and Vladimir-Suzdal went to Novorossiya, while those from Kiev and the South in general went into OTL Ukraine (which was mostly settled by Kumans at this time).
When returning merchants spread tales about the riches of the new lands, the competition for it began. In a War between Vladimir and Novgorod 1469-72, Novgorod lost the right to trade in the areas east of Volga and Kama - thus being cut off from Novorossiya now. And in another Border war between Vladimir and Chernigov 1483-89, Vladimir won again, thus kept the Southern Russian states from expanding east of the Volga.
Since the 1490s, After the taxes were raised in Old Russia, even more settlers went East and South.
Progress of settlement
1470: Tobolsk at Tobol river founded.
1500: Settlements in Novorossiya as far as Ob and Irtysh rivers.
~1510: Settlements in Novorossiya as far as Yenissei river.
~1540: Settlements in Novorossiya at Lake Baikal.
~1550: Settlements in Novorossiya at Lena river.
~1560: Settlements in Novorossiya as far as upper Amur/Aigun river.
~1580: Settlements in Novorossiya have reached the Pacific. Since the Russians now have settled all of OTL Ukraine and Siberia, they start to expand to other areas.
1583: Alyeska (Alaska) discovered by Russian sailors.
1590: Kuriles annexed by Novorossiya.
1637: Novorossiyans found first settlement on Ezo (OTL Hokkaido).
1644: Novorossiya claims all of Alyeska.
1500: Vladimir 9 million, Kiev-Chernigov 10.5 million, Novorossiya 0.8 million
1550: Vladimir 12 million, Kiev-Chernigov 13.5 million, Novorossiya 2.5 million
1600: Vladimir 16 million, Kiev-Chernigov 18 million, Novorossiya 5 million
During the war: Vladimir 20 million, Kiev-Chernigov 22 million, Novorossiya 7.5 million
1512-17: Novgorodian War. Vladimir-Suzdal defeats the old competitor, annexes it. Many Novgorodians who miss their old freedom go to Novorossiya.
1538-40: Clash with Choresmian troops and Mongol (and related) warriors. They ask the Grand Prince for help, which they don't get - which they won't forget.
1552: Mongols attack a Novorussian caravan at the Silk Road. When the uninterested Grand Prince again disappoints the merchants, they decide to act.
1561: Novorossiyan cities threatened by Mongols and Muslims form "unofficial official" armies to defend them, instead of the irregular defenders they had so far.
1580s: The "parties" of Novorossiya start to take form - on the one hand, the "Westerners" who want to preserve ties to Vladimir-Suzdal and Russian traditions, OTOH the "Chunkvophiles" who want to introduce Chinese thoughts they find useful. Ironically, the former are strict defenders of the democratic rights (as in the vyetjes), while the latter have at least some sympathies for the imperial idea.
1589: Novorossiyan cities start to develop a defense network to coordinate their military.
1592: Vladimir-Suzdal attacks Sweden. For the purpose of the war, a new tax is made, which also has to be paid in Novorossiya. Many people there are angry about the tax.
1617-32: Novorussian War of Independence. When Kiev-Chernigov supports them, Vladimir has to accept that they leave. The republic of Novorossiya is founded. Capital becomes Yenisseisk.
1638: Novorossiya gives itself the first constitution.
Relationship with China
1516: Russian merchants find their way into Hong China. On their return they spread tales about "Chunkvo" (derived from Zhongguo), which even reach the court in Vladimir. Novorossiyan traders start to get rich on the trade with goods from China.
1521: Novorussian (Siberian) merchant families officially are granted the right by the Grand Prince of Vladimir to trade with China.
1552: Another delegation sent to the Hong emperor is successful: In exchange for them sending a tribute of furs, wax and honey, he allows them to found trade stations in his empire.
1591: In Yenisseisk (at OTL Krasnoyarsk's site), a school for Chinese studies is founded, which will later develop into the first university of Novorossiya.
Since 1600: Novorossiya undergoes an amazing modernization process, introducing many advances imported from China. Except for Chinese arts and science, the changes also concern the life of the common man, like drinking tea, gambling with cards instead of dice, wearing clothes with a more Chinese style.
1613: Chinese school of Yenisseisk expands so that everything concerning China is taught: Their language, their technologies, their culture, their strategy, their philosophy, everything. Some of this knowledge will filter to Old Russia, together with republican ideas (see below!).
1629: Novorossiya builds the first Russian dry dock at Patsifikskaya (OTL Vladivostok), with the help of Chinese artisans, paid by money earned with otter pelts sold to China.
1647: Novorossiyan republic makes a contract with the Hong empire to fight the people north of the Chinese Wall. The emperor sends them strategical, scientific and technical advisors.