The arrival of Croats to the Adriatic caused big demographic changes on all islands and the Kornati were not an exception. The Roman population was forced by the Croat invasion to flee the mainland and find sanctuary on the islands.
As the sea was not for long a barrier for the Croats, there occurred a conflict between them and Venice who was trying to dominate the Adriatic. This era – the decline of Byzantium and rise of Venice and the arrival of the Croats to the Adriatic – was critical for the inhabitancy of the Kornati. The Kornati became a very unsafe area so it is surmised there were no permanent residents on the islands until the 13th century.
The Kornati started coming to life again in the 13th century. There are some very interesting buildings from the Middle Ages in the Park. The most impressive of them is certainly the little church of Our Lady of Tarac (Gospa od Tarca), a humble one-nave sacral building (a typical rural late Romanesque church), built in the place of the early Christian basilica, most probably with the stones of the older church. It is not clear when Gospa od Tarca was built: it is postulated that it was built in the 12th-13th century, in the 14th century, or sometime in the 15th-16th century. Masses are still celebrated in the church (every first Sunday in July), but they are no longer just religious observations as they became a tourist attraction of the area. Remains of a salt warehouse and submerged remains of salt pans in the Lavsa Bay also date to the Middle Ages (probably the latter half of the 14th century).