 In the Early Medieval period, Byzantine Dalmatia was ravaged by an Avar invasion that destroyed its capital, Salona, in 639 AD, an event that allowed for the settlement of the nearby Diocletian's Palace in Spalatum (Split) by Salonitans, greatly increasing the importance of the city.The Avars were followed by the great South Slavic migrations.The Slavs, loosely allied with the Avars, permanently settled the region in the first half of the 7th century AD and remained its predominant ethnic group ever since.