Rūm, also romanized as Roum, is a derivative of Parthian (frwm) terms, ultimately derived from Greek Ῥωμαῖοι. Both terms are endonyms of the pre-Islamic inhabitants of Anatolia, the Middle East and the Balkans and date to when those regions were parts of the Eastern Roman Empire.
A view showing several floors of an underground Rûm city in Turkey.