Estonia was Christianised by the Catholic Teutonic Knights in the 13th century. The Protestant Reformation led to the establishment of the Lutheran church in 1686. Before the Second World War, Estonia was approximately 80% Protestant, overwhelmingly Lutheran, followed by Calvinism and other Protestant branches. Many Estonians profess not to be particularly religious, because religion through the 19th century was associated with German feudal rule. There has historically been a small but noticeable minority of Russian Old-believers near the Lake Peipus area in Tartu County.