My Little Pony: Friendship is Magic: Warlords of Tambelon: Chapter 1: Prologue:

From the memoirs of Scorpan:

On this, the 1011th anniversary of the re-unification of Tambelon, I record my memoirs, which may detail the re-unification itself. I begin with the event that may very well haunt me until the day I, someday, pass on:

Long ago, when I was younger and more innocent, my brother, Tirek, seeking to increase the power of our land, traveled with me to Equestria to steal its magic. While there, we became separated.

It was during this time that I made the acquaintance of a wizard named Star Swirl, who taught me much. The three tribes of ponies were still getting used to being unified under one flag, at the time, but Star Swirl and his allies had great hopes for them, and the nation they could create together, under young (during that time) Princesses Celestia and Luna.

Realizing that I had been wrong in my judgement, I tried to explain what I had learn to my brother, but he refused to listen. I turned to Celestia and Luna, who ultimately banished Tirek to Tartarus, to my great sorrow.

To make matters worse, when I returned to my parents and told them what had happened, my father was furious… though not with me. To my mother and I's sorrow, he disowned Tirek, and declared me heir to the throne.

Little did I realize then, that this would be where an even GREATER problem would begin…