 A long @-@ running rivalry between <unk> and <unk> began in the 6th century , with each of the two cities forming its own network of mutually hostile <unk> <unk> against each other in what has been likened to a long @-@ running war between two Maya <unk> . The kings of these two capitals adopted the title <unk> ' , a term that has not been precisely translated but that implies something akin to " high king " . 
