Siberia was a location in Russia.
In 1927, a Vondraxian orb was found in Siberia. One person was exposed to the tachyon radiation. The KVI tried to extract the tachyons by killing him, but they dissipated after death. (PROSE: Trace Memory)
During World War II, the curator of the Palace Museum in Leningrad fled to Siberia with the collection of treasures after the invading armies of Nazi Germany surrounded the city. (PROSE: Cabinets of Curiosities)
In one possible timeline where Earth was eventually designated Orphan 55, Novosibirsk was destroyed and left in ruins due to the effects of nuclear war and climate change. Tranquility Spa was built near these ruins, in former Siberia, where it was protected by an ionic membrane.
When the Thirteenth Doctor and friends visited, the spa came under attack by Dregs, and all survivors ventured out into the barren landscape beyond. It was in an underground tunnel, beneath Novosibirsk, that the Doctor realised they had been on Earth all along. (TV: Orphan 55)