The roots of Kendo, The Way of the Sword, are to be found in Kenjutsu, the art of wining a real fight with real swords. Japanese historians mean that there were three periods in the ancient history of swordsmanship: Joko-ryu, Chuko-ryu and Shinto-ryu (the ancient, middle and new styles).
It is difficult to find accurate dated historical studies about Kenjutsu but in the three volumes of Kojiki that covers the history of Japan from mythological age down to the reign of Empress Suiko (592-628 CE) and the 30 volumes of the Nihon-shoki, completed in 720, Kunimatsu no Mahito, a famous swordsman, is mentioned as founder of Kenjutsu. His fencing style, Kashima No Tachi (Kashima Shrine style), still exist.