▁River . ▁ ▁The ▁following ▁three ▁dec ades ▁were ▁the ▁p inn acle ▁of ▁Y iqu ▁power , ▁with ▁its ▁territory ▁dou bling ▁to ▁almost ▁. ▁ ▁At ▁this ▁point , ▁Y iqu ▁had ▁become ▁a ▁major ▁threat ▁to ▁Q in , ▁who ▁had ▁to ▁sole ly ▁focus ▁on ▁dealing ▁with ▁this ▁north - western ▁neighbour ▁and ▁thus ▁became ▁marg inal ised ▁by ▁other ▁major ▁Central ▁P lain ▁v ass als ▁states ▁to ▁the ▁east . ▁ ▁In ▁ 3 6 1 ▁BC , ▁Duke ▁X iao ▁of ▁Q in ▁asc ended ▁as ▁the ▁r uler ▁of ▁Q in , ▁and ▁appointed ▁Wei ▁Yang ▁in ▁ 3 5 9 ▁BC , ▁who ▁en act ed ▁a ▁series ▁of ▁legal ist ▁re forms ▁that ▁greatly ▁strength ened ▁the ▁state ▁of ▁Q in . ▁ ▁In ▁ 3 3 2 ▁BC , ▁King ▁H ui wen ▁of ▁Q in ▁dispatch ed ▁G ong sun ▁Yan ▁( 公 <0xE5> <0xAD> <0xAB> <0xE8> <0xA1> <0x8D> ) ▁to ▁attack ▁Wei , ▁killing ▁ 8 0 , 0 0 0 ▁enemies ▁and ▁capt uring ▁X ihe ▁Command ery ▁( 西 河 郡 ) ▁and ▁Shang ▁Command ery ▁( 上 郡 ). ▁ ▁At ▁the ▁time , ▁Y iqu ▁was ▁having ▁domestic ▁disput es , ▁so ▁the ▁Q in ▁army , ▁with ▁its ▁mor ale ▁boost ed ▁by ▁the ▁recent ▁vict ories , ▁inv aded ▁Y iqu ▁under ▁the ▁pre text ▁of ▁helping ▁to ▁qu ell ▁Y iqu ' s ▁cha os . ▁ ▁They ▁were ▁able ▁to ▁subject ▁Y