The central part of the territory is known as the historical region of Ingria (or the land of Izhora) and in the 17th century, after most of the present-day territory of Leningrad Oblast was captured by Sweden with the Treaty of Stolbovo of 1617, became subject to substantial Finnish Lutheran population influx from Finnish Karelia (which included Karelian Isthmus, the northwestern part of present-day Leningrad Oblast) and Savonia. Having faced the religious pressure from Lutheran pastors and Swedish authorities, local Orthodox population of Russian and Finnic ancestry massively fled from Ingria to neighbour Russian provinces, so Ingrian Finns soon became the dominant ethnic group.