So when China offers to build a new railway into the "ickystan" region of central Asia, the Russians brush up on their own history and worry.
Something Russia does not like to discuss openly is the fact that Chinese railroads extending into Central Asia would make it easier for China to carry out major military operations in the area. With rail lines extending deep into Central Asia China could more easily threaten a long feared invasion of Russia to take back the eastern territories that many Chinese believe are theirs. Such an invasion is unlikely as long as Russian nuclear weapons can hit China (via missile or bomber). But if that threat were diminished, a rail network in Central Asia that is connected to China would be a much more fearsome prospect for Russia. In the meantime, such a railroad is going to hurt the Russian economy because Chinese firms will have cheaper access to Central Asia and will likely drive out more expensive Russian products.
not mentioned: That Vladivostok and eastern Siberia have more ties with China than Moscow.
And I still wonder who is funding the Sultan of swing Sulu's claim to Borneo...someone trying to split the united front against China's grab of the West Philippine sea? But is it Islamic "charity" money or Chinese money sweetening the pot?
800 thousand Filipinos have migrated there, but China is the main importer of their palm oil exports, and has many economic interests there.
(yes, in today's world, the Sulu dispute is connected with the Mindanao rebellions, but it was China who helped the Sultan stay in power in the Middle Ages and there remain a lot of Chinese in the cities running the place, just like the descendants of the Chinese merchants run the Philippine economy).
As a Yank, I have little patience with royalty who try to grab back "their land". The land belongs to those who work it, not some nincompoop whose sperm donor allowed him (or another of the many others claiming to be Sultan) to grab back their fiefdom.
As one sardonic Jewish carpenter once said: Let the dead bury the dead.
The American saying on this type of thing is "Who died and left you king", implying that no one should be able to push people around because of ancestral privilege.