After the Roman conquest of Illyria in 168 BC, Romans colonized and founded several cities in the region which they named Dardania. Ulpiana was one of the most important Roman cities in the Balkans and in the 2nd century BC it became a municipium. The city suffered tremendous damage from an earthquake in 518 AD. The Byzantine Emperor Justinian I rebuilt the city in great splendor and renamed it Justiniana Secunda, but with the arrival of Slav tribes in the 6th century the city again fell into disrepair.