Princess Celestia's best scholars believed that Eris ruled for over a century before Celestia and her sister, Luna, found a means of defeating Eris. Neil presumed these were the ancestors of Celestia, who started the royal dynasty. The result was the Spirit's petrification into stone on the flat mountain plateau that would later become the gardens for Canterlot Castle. Celestia and Luna were then crowned as rulers over the crumbling remains of Equestria, opting to take the title of Princess, and the rest was history.