The name 'Koro' first appeared in the chapter of the fourth year of the Showa era (837) of "Nitto guho junreiki" (The Record of a Pilgrimage to China in Search of the Law), which was described by Ennin, a monk who went to China for studying.
鴻臚の名は入唐留学僧円仁の『入唐求法巡礼行記』の承和(日本)4年（837年）の記述に初めて登場する。