Great Demon War
The Great Demon War was a cataclysmic event in Senecan history. The event predates the formation of Seneca as a complete country, in fact. Prior to the Great Demon War, Seneca was populated by six tribes of relatively ungoverned people. The demon invasion wiped out over two thirds of the population of Seneca, and convinced the six tribes to combine their strength to better combat the overwhelming threat.
Despite their combined efforts, the demons made excellent progress, and decimated any army sent to fight it. When all hope seemed lost, the six tribes prayed for salvation, and it came.
Seven warriors, who would come to be called the Seven Legendaries by the people they saved, appeared as though from nowhere. The seven of them, with their strengths combined, managed to fight off the entire army by themselves. The Seven Legendaries then united the remnants of the Senecan tribes and established Seneca as a unified country.