The Albanian diaspora has its roots in migration from the Middle Ages initially across Southern Europe and eventually across wider Europe and the New World. Between the 13th and 18th centuries, sizeable numbers migrated to escape various social, economic or political difficulties. One population, the Arvanites, settled Southern Greece between the 13th and 16th centuries assimilating into and now self-identifying as Greeks. Another population, the Arbëreshë, settled across Sicily and Southern Italy between the 11th and 16th centuries. Smaller populations such as the Arbanasi settled Southern Croatia and pockets of Southern Ukraine in the 18th century.