From around the time of Heian-kyo, the Sakyo area, which became the basis for the subsequent city of Kyoto, was called 'Rakuyo' after the Tang Dynasty Chinese capital Luoyang (Rakuyo in Japanese), and the area within the city was called Rakuchu, while the outside area was called Hendo (remote region) and later called Rakugai (refer to Kyoto and Rakuyo), but definitions were ambiguous.
平安京の頃から、後の京都の基礎となった左京地域を唐の都・洛陽に擬えて「洛陽」と呼び、市内を洛中（らくちゅう）、外側を辺土、後に洛外（らくがい）と呼んだが（京都と洛陽を参照）、具体的な定義は曖昧であった。