The Forest Territory that harbored the very first clans, the place where cats grew up knowing so well is being destroyed by the expansion of Two-Legs. The land wasn’t the clan’s anymore, so, in a unanimous agreement of all four clans they decided to leave in search of a new home.

StarClan has already given them a sign, a shooting star left a fiery trail in the sky that led to what will be a new land. But you’re going to have to get along with the cats from the other clans

Ngl I still can’t believe that the Great Journey in the book was a distance of like 460 miles