The remains of a 9th-century fortress covering 12ha, the age of which has not been determined, were unearthed in the centre of Nitra.
The main source of information about the polity now known as the Principality of Nitra is the Conversion of the Bavarians and Carantanians, a document compiled around 870 to promote the interests of the Archdiocese of Salzburg in Pannonia.