Discovery of building materials reveals ingenuity of Jomon ancestors
(Asahi Evening News Supplement, Sept. 5, 1998, retri. from the Niigata Prefectural Museum of History website)
Excavations at the Sakuramachi site, Oyabe City, Toyama Prefecture uncovered several building timbers approximately 4,000 years old. The building timbers were in the form of a wooden cross and had been joined together with a mortise and tennon joint. This technique, called watariago-shiguchi in Japanese, had never been found before in structures dating to the Jomon period. Previously it was thought this construction technique was first used in Japan in the the 7th century AD structure of Horyuji Temple.
Heritage of Japan 