Although the reasons behind making the images are not necessarily clear, they are believed to have been made in the Tenpyo era judging from their styles and the fact the word 'Tenpyo' written in black ink was found on the pedestal of one of twelve images.
造立の事情は必ずしも明らかでないが、作風や、12躯のうち1躯の台座から「天平」の墨書が見出されたことなどから、天平期の作と見なされている。