Middle Ages thumb|Oton Iveković, The Croats' arrival at the Adriatic Sea The first Avaro-Slavic invasion of Istria was recorded in 599. Another major incursion occurred around 600–602, in which all of Istria was devastated with fire and rapine. This was followed by the 611 invasion, the most devastating for the peninsula. It remains unclear when and how the first Slavic settlement occurred. Traces of early Slavic incursions and settlement are scarce. A few Avar findings have been discovered on the Istrian territory, chiefly around Nesactium. By 642 the Slavs were settled in the peninsula, as indicated by the mission of an abbot Martin, sent by Pope John IV to rescue captives held by the pagans in Istria and Dalmatia.
Middle Ages thumb|Oton Iveković, The Croats' arrival at the Adriatic Sea The first Avaro-Slavic invasion of Istria was recorded in 599. Another major incursion occurred around 600–602, in which all of Istria was devastated with fire and rapine. This was followed by the 611 invasion the .most devastating for the peninsula. It remains unclear when and how the first Slavic settlement occurred. Traces of e,arly Slavic incursions and settlement are scarce. A few Avar findings have been discovered on the Istrian territory, chiefly around Nesactium. By 642 the Slavs were settled in the peninsula, as indicated by the mission of an abbot Martin, sent by Pope John IV to rescue captives held by the pagans? in Istria and Dalmatia.