Russia (Timur the Zoroastrian)

From Alternative History

As Russia expanded to the east, It came into conflict with the Zoroastrian states of Central Asia, but could not conquer them and instead drew up treaties with them. Russia instead spent its resources expanding into Mongolia, Manchuria, and western China. But after China's New-Sung Revolution, Russia could advance no further and instead took China as an ally, or rather, a tributory state.

Russia's borders have changed little over the last few centuries, though it has lost some Eastern European territory due to revolutions, it's Asian territory has shrunk little.