When was Kyoto first called Kyoto? With the relocation of the nation's capital by Emperor Kanmu in 794, the new capital was established as Heiankyo. But it was often called by other names such as "kyo," "keishi" and "kyo no miyako."
All the kanji characters in these words have the same meaning as miyako, which originally meant "home of the emperor." However, two of them - "kyo" and "miyako" - were combined to specifically refer to the city of Kyoto.
Originally common noun
Before the establishment of Heiankyo, other places where the emperor used to live were also called "kyoto."
The word "kyoto" became a proper noun referring to the city that is presently Kyoto late in the 11th century and became widely accepted in the following period called the "insei-ki" (a period when retired emperors recaptured the reins of government), said Hisashi Oboroya, an honorary professor of Doshisha Women's College of Liberal Arts.
The name "kyoto" had been previously used, but as a common noun. Whether it is a common noun or a proper noun is judged from the way in which it is used.
"Fuso Ryakki" (A brief history of Japan), which describes the rebellion of Taira no Masakado, says in reference to events one day in 940: "The capital is agitated. Masakado's forces have advanced into kyoto." In this sentence, "kyoto" is a common noun.
"Gonijo Moromichi-ki" (The diary of Fujiwara no Moromichi) describes visiting the Uji Imperial villa at around 8 a.m. one day in 1096, leaving after the sunset and arriving in Kyoto at around 8 p.m. In this context, the word was likely used as a proper noun.
source by the-japan-news