Tongtian Sword Emperor

Three thousand years ago, Xu Aotian, the peerless Sword Emperor of Tianyu Continent, together with the Thunder Emperor, Sword Emperor, and Demon Emperor resisted the invasion of the Dongyi tribe. However, they were accidentally attacked and killed at the critical moment of the battle. Three thousand years later, Xu Aotian was reborn as Li Aotian, a small figure in Qianye County. The world is unpredictable and the sea has changed. Three thousand years have passed. Xu Aotian was surprised to find that his name was not mentioned in the records of the battle to resist the invasion of the Dongyi tribe, and the sword realm he created with his own hands actually fell apart and disappeared completely in the long river of history. Who is behind this? What happened three thousand years ago?