In the Red Alert era, Siberia became the staging ground for Gradenko's invasion of eastern Asia and also, three battles were here between the Soviets and the Allied Forces. The battles took place during Counterstrike in 1948.
In the Tiberium era, Siberia remained part of GDI-controlled Russia, although Nod activity was a constant threat. Given the empty, isolated and inhospitable nature of large parts of Siberia, it is no surprise that Nod would base some of its more notorious secret projects here, where Kane's plan can be carried out far from prying eyes. The most notable of these is undoubtedly the Marked of Kane project. One day, GDI decided to do something about this and built a large base in the heart of Siberia to monitor things. Unfortunately, it was built right on top of where the Marked of Kane cyborgs were lying dormant underground. When they were activated in 2052, the base was promptly overran and razed.