if we use your arguement and logic then the whole world will full of no man's land except some little patch of territory.But if we're going by the definition of core Sinitic lands, then China should be a lot smaller
Or even smaller than that
then all turk and mongol should only live in mongolia particulary near altaic mountain west mongolia
then all white whatever their group (germanic slavic romanic) should go back and live in europe only
then all austronesian that live in southeast asia and pacific islands must go back to taiwan island, etc.