ijo ▁were ▁written . ▁ ▁Kim ▁Che ont a ek ' s ▁anth ology ▁represents ▁a ▁change ▁in ▁the ▁author ship ▁of ▁s ijo .   At ▁first , ▁s ijo ▁were ▁primarily ▁composed ▁by ▁the ▁y ang ban ▁arist ocracy ▁and ▁entertain ers ▁of ▁the ▁K isa eng ▁class .   However , ▁by ▁the ▁mid - se vent e enth ▁century , ▁the ▁j ung in ▁or ▁“ prof essional ▁class ” ▁were ▁compos ing ▁s ijo ▁as ▁well .   This ▁also ▁coinc ided ▁with ▁a ▁new ▁form ▁of ▁s ijo ▁called ▁“ n arr ative ▁s ijo ” ▁( H ang ul : ▁ 사 설 시 조 / H anja : ▁ <0xE8> <0xBE> <0xAD> <0xE8> <0xAA> <0xAA> 時 <0xE8> <0xAA> <0xBF> ), ▁in ▁which ▁the ▁first ▁two ▁lines ▁were ▁greatly ▁length ened .   This ▁expansion ▁is ▁likely ▁a ▁development ▁from ▁the ▁so - called ▁“ ir regular ▁s ijo ” ▁( H ang ul : ▁ 엇 시 조 / H anja : ▁ <0xE6> <0x97> <0x95> 時 <0xE8> <0xAA> <0xBF> ), ▁in ▁which ▁there ▁was ▁a ▁minor ▁length ening ▁of ▁one ▁of ▁the ▁first ▁two ▁lines .   Wh ile ▁there ▁are ▁very ▁few ▁remaining ▁irregular ▁s ijo , ▁and ▁the ▁form ▁has ▁not ▁been ▁rev ived , ▁there ▁is ▁a ▁s izable ▁body ▁of ▁narr ative ▁s ijo ▁and ▁the ▁form ▁continues ▁to ▁evol ve . ▁ ▁P ' ans ori ▁ ▁( H ang ul : ▁ 판 소 리 ) ▁is ▁another