Thirty-five hundred years ago, the peaceful world of the Aborigionals came to a violent end. The most ancient of sagas, the Lexor Odixan r Zos, records how Zos Pater, Father of Gods and Men was angry at his children and sought to remove them from his world. To do this he enlisted Aeris, Daughter of the Night and Goddess of Chaos, Discord and Strife, to sow discord among gods and men. Thus, war spread across the world, and brother turned upon brother. Eris, however took pity upon men and caused a great storm to rise up, and carry them off to a new land where they would be free from the wrath of Zos. The Andrean Calendar begins with this mythical event, believed to have occurred 3665 years ago. 

While the sagas are highly dubious historically, what is known is that approximately 3500 years ago, warriors who called themselves the Keltani Achean arrived on the north coast of Andrea. From there they spread out and where they went, the Aborigionals were no more. By 2024 BCE they had conquered both the coast and the plains. Their bronze weapons and horse drawn chariots overwhelmed the people of the lowlands. The Aborigionals of the central highlands put up a stiff resistance however, and a thousand year struggle with them began. As the original Achean population increased, petty lords began to gain power, until a thousand tiny kingdoms dotted land. 

Recent historical and archeological studies suggest that the Keltani Achean were refugees from the Valanian invasion of Thesia. How they got to Andrea from Thesia is unknown, but the journey took atleast 100 years, during which time they lost much of their culture and civilization. The development of the Thesian refugees know as Keltani Acheans would take a very different course in later years than that of thier cousins across the sea. To this day linquistic ties can still be seen between Thesians and Andreans.