Kartli (Georgian: ქართლი [kʰartʰli]) is a historical region in central-to-eastern Georgia traversed by the river Mtkvari (Kura), on which Georgia's capital, Tbilisi, is situated. Known to the Classical authors as Iberia, Kartli played a crucial role in the ethnic and political consolidation of the Georgians in the Middle Ages. Kartli had no strictly defined boundaries and they significantly fluctuated in the course of history.