Continuous occupation true, but by relatively small Turko/Mongol tribes eking out an existence hunting and fishing. That's not most people's definition of any sort of a quasi-major trade nexus or caravan hub. Within historical times the caravan routes (silk road etc.)ran through southern Asia for obvious reasons.
True. There was trade along what was to become the Silk Road 2,000 years before it was called that.
Frankly, I don't know much about this area. (Siberia)
However, don't forget that the Ainu and the Jomon of Japan must have migrated through there at some time in the past. The oldest Jomon skeleton found in Japan is 13,000 years old.
Then we were suprised by these folks in China The Curse Of The Red-Headed Mummy. I'm in the process of re-reading Victor Mair's book, The Tarim Mummies, for the third time. I'm beginning to think that the Great Wall of China was built to keep out Caucasian 'Mongols' (Barbarians) from the north.
Maybe some of these Siberian folks?