It looks to me that China has decent relations with Russia, Mongolia, and even central asian Kazakhstan/Kirgisia/Tajikistan (of course there are some ethnic and economical tensions dragging this back, not to mention the issue of Uighurs who are related). China also has good relations with Pakistan.
Mongolia is an interesting case. Its independence is guaranteed by Russia, otherwise China would likely have swallowed it in the 1950s or so, much like Tibet.
But Mongolia, sitting between two authoritarian powers, is nowadays a stable democracy with regular transfers of power between opposing parties.
I wonder if this can last. Their best chance is actually the fact that they aren't very prominent on the international stage and probably not worth a conquest or hostile takeover right now.
* Colonizing by almost of the world's super power. It's like being abused by US China (todayas China) Russia France UK Germany etc. Think a moment how can a nation today fend off these powers and remain an integral nation. Yet, China managed to do that.
* During WW2, China faces Japan, China essentially is an agrarian society facing an advanced industrial nation Japan, with considerable resources and man power. China almost lost 1/3 of its territory. Yet the nation standed up, and emerged more coherent and unified than before WW2.
* The so-called insane CCP managed to install strong control over Tibet and Xinjiang, right after WW2, right under the threat of USSR. The ability to manipulate Stalin, is indeed insanely smart.
* CCP fought a series wars after WW2 never lost, and have all succeeded to achieve it's political objective. Indian border war made sure India as a nation lost its aggression towards China for half a century, Korea war installed a fear and awe by us military men towards Chinese army; the Vietnam war effectively ensure no single nation able to challenge China's long term superemcy in South East Asia.
* They are the only equal partner in the cold war containment over USSR, basically practiced the strategy by their own strategic initiative and offered proactive support across the globe for that strategy to work.
* They initiated opening up and internal reform, transformed 1B people from a USSR style economy into the second largest in USD number, and the largest in purchasing power. Where as the same reform effectively triggered the collapse of USSR, which had 1/4 of the population of China.
* They effectively are challenging US supremacy in all aspects and are winning in many. Basically unimaginable since 1920s.
Call me stupid, but I think they are not only sane, they are probably so sane that random people like you are not able to grasp their genius...
> the Vietnam war effectively ensure no single nation able to challenge China's long term superemacy
I hope you realize that China flat out lose this one?
> They are the only equal partner in the cold war containment over USSR
This is not true and embarrassingly so. That's like Mazepa declaring himself the only equal partner of Charles XII (google it up). Triple embarrassing for chinese communist party. Probably fourthly embarassing in the context of USA "containing" China right now.
Although Vietnam continued to occupy Cambodia, China successfully mobilized international opposition to the occupation, rallying such leaders as Cambodia's deposed king Norodom Sihanouk, Cambodian anticommunist leader Son Sann, and high-ranking members of the Khmer Rouge to deny the pro-Vietnamese Cambodian People's Party in Cambodia
China caused Vietnam to suffer from serious economic and military hardship by threatening to launch a second invasion, and by supporting Pol Pot guerrillas in Cambodia.
Although unable to deter Vietnam from ousting Pol Pot from Cambodia, China demonstrated that its Cold War communist adversary, the Soviet Union, was unable to protect its Vietnamese ally.[19]
China had a sadistic crazy butchering ally, they've failed to keep that ally regime from being toppled by Vietnam, China has invaded Vietnam but was met by stiff resistance and had to retreat (which looks much more like a defeat rather a draw, especially given the difference in size between parties) and of course China no longer had the Cambodia - Vietnam did not occupy it either but I'm not sure they seriously planned to.
I'm really weak in that kind of history so I may get everything off, but that's what it looks from the outside.