After 4,000 years of dynasties, beginning with the Xia in the 2100s BCE, China had a rough transition to modernity. The country would not be truly unified until after World War II and the victory of the Communist Party in 1948.
Only China can have a Civil War while having WWII. It’s a big mess.
But China has not yet 100% Truly Unified since Republic of China retreated to Taiwan and is still well and alive now while the communist People’s Republic of China stays in… well, mainland China.
Technically RoC is not accepted by the UN as an actual country, even though it’s RoC that founded the UN (and PRoC took over it’s place after their victory), but we do have our own passport, government, money etc., and the US sure likes to mention us whenever it wants to poke at PRoC, so we are a like a Schrödinger’s Country lmao