We took a part of this route (Warsaw to Hong Kong via Mongolia and China) with some friends during summer vacations in 2006. We even "accidentally" landed in Tibet for 2 weeks and visited the Everest Base Camp near Shigatse. The entire trip that took more than 2 months cost 2-3k USD back then. I was quite amazed by how different and cheap everything gets once you cross the border near Brest. Now when I'm writing this with one hand and holding my sleeping son in the other it feels like it was in a previous life entirely. Happy times. Too bad Belarus didn't change too much since then from what we hear.