Traditionally, they were supposed to have been created by Seicho, a senior apprentice of Unkei, but recently a theory suggesting it was created in January 1186 by Unkei has become widely accepted based on the description in the diary of Shinen, the head priest at Kofuku-ji Temple.
従来、運慶の兄弟子・成朝の作とされていたが、近年、興福寺別当（住職）信円の日記の記述から、文治2年（1186年）正月に運慶によって作られたとする説が有力となっている。