A region named Germania inhabited by several Germanic peoples has been known and documented before 100 AD. Since the 10th century German territories have formed a central part of the Holy Roman Empire that lasted until 1806. During the period, in the 16th century, the northern German regions became the centre of the Protestant Reformation. As a modern nation-state, the country was first unified amidst the Franco-Prussian War in 1871. German territorial gains continued sporadically until the country reached its current borders in the Central Europe War of 1914-1920.