Yeah, China hasnt exactly forgiven and forgotten how Tsarist Russia took advantage of their political, social, and economic weaknesses and inability to confront European and Japanese interference in the 1870's and 1880's when Russia forcibly moved into and annexed large parts of Eastern Siberia (completing a process begun by Catherine the Great) and founded the Far Eastern cold-winter port of Vladivostok. Even though Russia, previously the USSR, and China have been "freenemies" since the 1930's, there's still a major amount of hatred, below-surface tension, and Chinese have always felt that the Soviets held this barely-concealed racial and cultural superiority and arrogance over them even 55-60 years ago plus their were some nasty border clashes in 1969-70 that nearly went nuclear and in fact, Soviet U.S. ambassador asked his State Department who we (U.S.) would likely support if a Sino-Soviet border war went nuclear and Nixon ultimately sided with the Chinese (thus the "China card" was created). Ethnic Chinese actually vast outnumber their Russian counterparts in eastern Siberia by 50 or 100-1 population ratios. Both sides are glaringly aware of this imbalance and Chinese are probably gleefully happy that the Russians know they know that, too.