The medieval Georgian Chronicles present an eponymous ancestor of the Kartvelians, Kartlos, a great-grandson of Japheth. However, scholars agree that the word is derived from the ''Karts'', the latter being one of the proto-Georgian tribes that emerged as a dominant group in ancient times. The name ''Sakartvelo'' (საქართველო) consists of two parts. Its root, ''kartvel-i'' (ქართველ-ი), specifies an inhabitant of the core central-eastern Georgian region of Kartli, or Iberia as it is known in sources of the Eastern Roman Empire. Ancient Greeks (Strabo, Herodotus, Plutarch, Homer, etc.) and Romans (Titus Livius, Tacitus, etc.) referred to early western Georgians as Colchians and eastern Georgians as Iberians (''Iberoi'' in some Greek sources). The Georgian circumfix ''sa''-X-''o'' is a standard geographic construction designating "the area where X dwell", where X is an ethnonym.