What is "iwajuku"

is an archaeological site in Midori, Gunma Prefecture, Japan. The site was excavated in 1949 by amateur archaeologist Aizawa Tadahiro, who confirmed the existence of two cultural strata, one of which contained small tools such as Projectile points and blades made of obsidian and agate from the Japanese Paleolithic period. This overturned the prevalent theory that human habitation of the Japanese archipelago began with the Jomon period, and indicated that humans had resided before the 10th millennium BC, or since the end of the last ice age

The site was designated a National Historic Site by the Japanese government’s Agency for Cultural Affairs in 1979.