When there were difficult passes or river crossings on the main routes, hime kaidō were established to avoid them.
Because there were fewer travelers, less danger, a lower chance of an attack by bandits (compared with the main route they were avoiding), it was said that people could relax while traveling the route.
There were different definitions of what made a hime kaidō, as some detours just went around one difficult area, while others were much longer and avoided most of the dangerous routes.
Because of the various definitions, the Nakasendō was sometimes referred to as a hime kaidō, because the distance was much greater and the danger was much less than that of the Tōkaidō, which started and ended at the same location.
Other features employed the same naming conventions, including hills.