In Fukuoka Prefecture, Japan, archaeologists have discovered several 1,800-year-old offering pits containing highly polished 'bronze mirrors' arranged in a circular pattern. The mirrors, dating to the late Yayoi Period, were placed face-up to reflect the sky, a practice researchers link to early proto-Shinto festivals aimed at 'calling back' the sun after the winter months.
The site, located on a hill overlooking the Genkai Sea, also yielded fragments of ceremonial wooden clappers and remains of ritual sake vessels. This configuration provides the earliest physical evidence for the Amaterasu-focused solar festivals that would eventually evolve into the complex seasonal matsuri seen across modern Japan today.