Ukyo, being located on damp ground, declined over the years, and Rakuyo was mainly used to refer to Heian-kyo as the population and main facilities were concentrated in Sakyo.
その後、低湿地であった右京が寂れ、人口も御所などの重要施設も左京に集中するに伴い、洛陽が平安京の代名詞となっていった。