Simplify the following text for a Grade 6 native English-speaking person.
Original: ( Reign :661 - 681 ) , He was Family name was Kim ( korea : ê , Hanja : é ` ) , Surname was Beopmin ( korea : ë ë 1\/4 , Hanja : æ æ ) . Munmu was the first ` unification of Korean ' to monarch , the Korean people of Usually call of Munmu the Great ( ë ë ë ì , æ -- æ å ç ) .
Simplified: He was born Prince Beommin ( ë ë 1\/4 , æ æ ) , and took the name Munmu when he succeeded his father to the throne .