▁year ▁in ▁exchange ▁for ▁sending ▁t ribute ▁to ▁Korea ▁and ▁a iding ▁to ▁stop ▁any ▁Wa egu ▁coast al ▁pir ate ▁ra ids ▁on ▁Korean ▁ports . ▁ ▁On ▁the ▁northern ▁border , ▁Se j ong ▁established ▁four ▁for ts ▁and ▁six ▁posts ▁( ▁) ▁to ▁saf egu ard ▁his ▁people ▁from ▁the ▁J urch ens , ▁who ▁later ▁became ▁the ▁Man chus , ▁living ▁in ▁Man ch uria . ▁In ▁ 1 4 3 3 , ▁Se j ong ▁sent ▁Kim ▁J ong - se o , ▁a ▁government ▁official , ▁north ▁to ▁f end ▁off ▁the ▁J urch ens . ▁Kim ' s ▁military ▁campaign ▁captured ▁several ▁cast les , ▁pushed ▁north , ▁and ▁restored ▁Korean ▁territory , ▁roughly ▁the ▁present - day ▁border ▁between ▁North ▁Korea ▁and ▁China . ▁ ▁During ▁the ▁rule ▁of ▁Se j ong , ▁Korea ▁saw ▁adv ances ▁in ▁natural ▁science , ▁agricult ure , ▁literature , ▁traditional ▁Chinese ▁medicine , ▁and ▁engineering . ▁Because ▁of ▁such ▁success , ▁Se j ong ▁was ▁given ▁the ▁title ▁" Se j ong ▁the ▁Great ". ▁The ▁most ▁remembered ▁contribution ▁of ▁King ▁Se j ong ▁is ▁the ▁creation ▁of ▁H ang ul , ▁the ▁Korean ▁alphabet , ▁in ▁ 1 4 4 3 ; ▁every day ▁use ▁of ▁Han ja ▁in ▁writing ▁eventually ▁was ▁sur pass ed ▁by ▁H ang ul ▁in ▁the ▁later ▁half ▁of ▁the ▁ 2 0 th ▁century . ▁ ▁Six ▁mart y red ▁minister s ▁After ▁King ▁Se j ong ' s ▁death ,