 The region of Mačva or Macsó probably came under Hungarian administration after the death of Byzantine emperor Manuel I Comnenus in 1180.It was first known as the Lower Syrmia (Sirmia ulterior) region.Rostislav Mikhailovich was mentioned among the dignitaries of Béla IV as Ban of Slavonia in 1247, and from 1254 onward he was mentioned as the Duke of Macsó (in Latin, "dux de Macho").