 However, – for the most part – the entire large Northern Swedish territory of Norrland was not Christianized until several hundred years after the rest of Sweden, and many northern areas such as Skellefteå remained unexplored well past the Middle Ages.Not before the very end of the 17th century did the indigenous Sami people of Northern Sweden begin turning to Christianity, much due to the efforts by the Northern Swedish superintendent Mathias Steuchius, who worked hard to accomplish this.Several Sami priests were killed for this reason.