It is believed that the name Tanzan (mountain of negotiation) came from an episode that FUJIWARA no Kamatari and Emperor Tenchi held a meeting in May 645 in Mt. Tonomine to discuss the Taika Reforms and, and later the mountain came to be called "kataraiyama" (mountain of chat) or "dansho no mori" (woods of consultation).
談山の名の由来は、藤原鎌足と天智天皇が、大化元年（645年）5月に大化の改新の談合をこの多武峰にて行い、後に「談い山（かたらいやま）」「談所ヶ森」と呼んだことによるとされる。