Winter of Broken States, 2090.
The old states that governed this region have fractured into a mosaic of rival polities. Beijing and Moscow each hold a diminished core and project influence into the fragmented middle, where river headwaters, rare-earth fields, oil basins, and the old rail corridors decide survival. The Amu Darya and Syr Darya no longer reach the shrinking Aral Sea, the passes of the Tien Shan, Pamir, and Altai are snowed shut through the winter, and the trans-steppe trade that once linked the great powers has fallen to a trickle. Most polities depend on water released upstream, on fuel from contested basins, and on roads and railways that cross territory they do not fully control.
On the first morning of 2090, the central authority that once held the Eurasian heartland has collapsed. Across the steppe a patchwork of successor polities now stands between two reduced great powers: the People's Republic of China and the Russian Federation. Republics, khanates, leagues, city-states, and warlord zones face a frozen winter of scarce water, contested minerals, and broken trade routes, and no outcome is yet fixed.
A polity holding a river's source may restrict the water reaching states downstream, and those downstream states may appeal to Beijing or Moscow to intervene on their behalf. The high passes of the Tien Shan, Pamir, and Altai close from November to April, blocking both armies and trade. A great power's formal guarantee of a small state is only credible while that power keeps a military force on the ground. Absorbing an unrecognized warlord zone is easy, while annexing the capital of a recognized state requires a declared cause. The Aral League's cohesion depends on the water released to it from upstream.