Splendid Valley was originally the home of the majority of Equestria's Diamond Dogs.
Splendid Valley was rich in gemstones, making it a very appealing place for Diamond Dogs to live. The valley was located close to Old Olneigh.
During the War
The ponies of Old Olneigh mined Splendid Valley for gems. The local Diamond Dogs resisted the pony intrusion on their lands, before they were forcibly relocated by the military. When Splendid Valley had been completely mined of its gemstones, the Ministry of Arcane Sciences built the Maripony facility over Splendid Valley; resulting in heavy taint pollution.
On the Last Day, the Maripony facility was disabled by a direct hit from a megaspell. The Diamond Dogs returned to Splendid Valley, where they would be contaminated by taint and become hellhounds.
Splendid Valley is populated by hellhounds and the area nearby is also populated by other creatures, like Alicorns and Floaters.
- Incorrectly refered to as Pleasant Valley in Project Horizons.