 According to the Yuan dynasty chronicle and Marco Polo 's accounts , a <unk> army " invaded " the <unk> territory of Gold <unk> , and was defeated by the <unk> army in April <unk> . The battle took place either at the <unk> valley ( in present @-@ day <unk> Prefecture ) or 110 km southwest at <unk> ( present @-@ day <unk> , <unk> Prefecture ) , which the <unk> called <unk> . 
