Not even true, korea existed long before the united states of autism
If you mean the joseon kingdom, that's true (before 1345 the peninsula was divided up by small warring kingdoms)
but it fell apart in the 19th century--internal corruption and various attempted invasions
then they had the "Korean Empire" from 1897 which was constantly fucked with by the Japanese, Russians and Chinese
then the Japanese invaded and told them what to do from 1910 to 1945
after the war the Soviets and Allies divided it along the 38th parallel and it's been two countries ever since
(who refuse to admit they are separate countries lolol)
korean history is a fucked up mess