Tom has heard legends of Jimmy's long distance journeys from one place to another, but never imagined undertaking one of his own.

However, when fate conspires to change him into Starswirl the Bearded, he is thrust into an adventure spanning an entire continent.

Part of the Legends of Equestria continuity. I strongly recommend you read these stories first, or else you'll have no idea what's going on;

https://www.fimfiction.net/story/433091/legends-of-equestria-the-sands-of-time

https://www.fimfiction.net/story/452751/legends-of-equestria-south-swamp-rag