Even in the face of Crusaders, by the time of Grand Duke Gediminas, the Grand Duchy of Lithuania expanded its influence until it formed the political centre of a vast and prosperous "pagan Empire". Lithuanians thus survived late into history as appreciable representatives of ancient European paganism, preserving this tradition as the official, state religion until the late 14th and early 15th centuries when Christianity was finally accepted by the states of the Grand Duchy, again for political reasons. Lithuanians were thus the last non-nomadic people in Europe practicing Indo-European polytheism. Unofficially, Lithuanians continued in their adherence to traditional paganism.