An essay on the history of the archbishopric department of the small city of Split on the Adriatic coast of Dalmatia was written in the XIII century. archdeacon of the local church Thomas. It is of particular interest to researchers and lovers of medieval history primarily due to the abundance of often unique historical material collected in it. Its content turns out to be much wider than the theme declared by the author himself, and in addition to local history plots covers the history of Dalmatia, Croatia and Hungary from early antiquity to the middle of the XIII century.