For a long time, China was not a "country" but more of a "group of territories" with multiple rulers and multiple republics leading it. China didn't become one unified country until 1949, when the Communist leader Mao Zedong created the "People's Republic of China" which was a unification of the many different republics and states/territories. I guess I meant to say that the oldest countries and kingdoms are the oldest ones to have a central ruler/general unification.