It is because they are same root. Korea was settled by Chinese; as a part of China, many Korean cultures and language are from mainland China and Korean are no different than Chinese genetically.
China, North Korea, and South Korea are all different countries.
The Yellow sea seperates china and south korea
China and Russia to the north and South Korea to the (surprise!) south
The neighboring countries of North Korea are South Korea, China, Russia, Japan, and Mongolia.
China in the north, South Korea in the south.
The only nation bordering China, Russia, and South Korea is North Korea.
China and North Korea have poorer economy compare to South Korea and Japan.
china and south korea. There are 3. North Korea also has a short border with Russia.
North Korea is the only nation to border both China and South Korea.
Japan, China, North and South Korea, India
China North Korea South Korea
North Korea and South Korea