According to most historians, the core territories of Moravia were located in the valley of the river Morava, today in present-day Czech Republic and Slovakia. Archaeological findings of large early medieval fortresses and the significant cluster of settlements growing around them suggest that an important centre of power emerged in this region in the 9th century. Early sources (Alfred the Great's contemporaneous translation of Orosius's "History of the World", which mentioned Moravia's neighbours, and the description of the travel of Constantine and Methodius from Moravia to Venice through Pannonia in the "Life of Constantine") also substantiate the traditional view.