 Complete the following phrase:  Thus the region has been depopulated for a long time. Only during times of repression the unfavourable high mountains were mainly populated by Montenegrin tribes. During the time of the Ottoman rule from the 15th to the 19th century the high karst was acting as main shelter for the Christian population. Military campaigns of Ottomans and Austro-Hungarians faced heavy losses while both great powers underestimated the difficulties to undertake successful raids in karst areas. The 