Wikipedia:
The waterfalls of the Slunjčica, together with the Plitvice Lakes, have not been well known for a long time due to their rather isolated position. In medieval times, the region around Slunj was known as no man's land (Latin terra nullius), an uncertain border region between Europe and the Ottoman Empire. Slunj later became a stronghold of the Military Frontier. The fortification of Slovin built by the noble Frankopan family was an esteemed secure refuge, around which the town of Slunj evolved. The fortress was destroyed in 1578 and later rebuilt. A period of increasing resettlement and economic prosperity followed the Treaty of Sistova in 1791.
Slunj was under French reign from 1809 until 1813. During this time, Croatian became the official language of the province. The house of the former governor general of the French Illyrian Provinces marshal Auguste Marmont in Slunj still exists.
With the invention of electric mills and massive emigration after the First and the Second World War, the economic significance of the mills of Rastoke dramatically declined. In 1969, Rastoke was put under national monument protection.
