"Kongōrikishi are an interesting case of the possible transmission of the image of the Greek hero Heracles to East Asia along the Silk Road. Heracles was used in Greco-Buddhist art to represent Vajrapani, the protector of the Buddha, and his representation was then used in China and Japan to depict the protector gods of Buddhist temples. This transmission is part of the wider Greco-Buddhist syncretic phenomenon, where Buddhism interacted with the Hellenistic culture of Central Asia from the 4th century BC to the 4th century AD.*"
According to Wiki
http://en.wikipedia.org/wiki/Shukongoshin
* "The origin of the image of Vajrapani should be explained. This deity is the protector and guide of the Buddha Sakyamuni. His image was modeled after that of Hercules. (...) The Gandharan Vajrapani was transformed in Central Asia and China and afterwards transmitted to Japan, where it exerted stylistic influences on the wrestler-like statues of the Guardian Deities (Nio)." (Katsumi Tanabe, "Alexander the Great, East-West cultural contacts from Greece to Japan", p23)
