Horses to be found back in the rough country, hidden away in the maze of pocket canyons where there was water and enough browning grass to keep them from straying.
People put their horses in the maze of pocket canyons to prevent them from being detected. 
mnli hypothesis: People put their horses in the maze of pocket canyons to prevent them from being detected.  premise: Horses to be found back in the rough country, hidden away in the maze of pocket canyons where there was water and enough browning grass to keep them from straying.