From Bulbapedia, the community-driven Pokémon encyclopedia.
The Valley of Steel (Japanese: ハガネの谷 Valley of Steel) is an anime-only location in Hoenn that appeared in the episode All Torkoal, No Play. It is located between Lavaridge Town and Mauville City.
Ash and his friends were traveling through it when they saw a lone Torkoal being attacked by a Skarmory and Magneton. After Ash saved it, Torkoal burst into tears and ran away. Later, Ash helped it defeat the Steelix who ruled over the valley and the Torkoal decided to join him.
Pokémon seen in the Valley of Steel