The Land Before it was Barovia

Long before Strahd came and civilized the valley, Barovia was once a wild land. The valley was largely populated by scattered tribes of ppl, usually no larger than a 50-150 ppl living in self-made houses and cabins. These people were used to the harsh landscape and were overall hearty, somewhat barbaric people. When Strahd came with his armies to invade and conquer the land, they put up a good fight but were no match for his tactics and his armies advanced weaponry.  
In addition, there were also groups of forest folk (druids) that lived in the wilds and didn't settle. The settled people and the forest folk have had a famously tumultuous relationship over the centuries, with periods of hate and periods of peace scattered across history.