Death Valley, also known as the Valley of Death, was a region of space that was located in the Badlands.
This location was a fabled area of derelict ships located deep within the plasma storm cloud of the Badlands. Its origins were unknown though it was believed to had been the sight of a massive battle. The area was later used as a base by the Maquis. Death Valley was considered too dangerous to visit by the time of the 24th century. Scavengers were noted to still visit the place where they looked for spare parts and salvage which meant it was a location where people traded with one another. There were lights in the area which were in reality crystalline clouds which glimmered like spun sugar which floated amongst the somnabulant ships. When plasma discharges exploded in the region, the crystal clouds glistened with every color in the spectrum.
The Talavians were known to reside in the outskirts of this area. This was not without a goal was it was believed there were treasures within the Valley. Derelict ships were known to be both very dangerous and strange. To the Talavians, the region was believed to had been haunted and sightings of derelicts growing more numerous over the years as well as driving most visitors away. The Cardassians were known not to visit the area. The Talavian belief in ghosts meant that the Valley of Death was a place of legend for them. However, the ghosts had a special place for they left gifts for the living within this location. Whilst this was what their beliefs told them, the area was actually home to an unknown form of phase shift which made it very dangerous.
In 2373, the secret Starfleet infiltration team hiding onboard the Orb of Peace were led to Death Valley by coordinates from the Romulan Hasmek. Once there, they met with a Talavian starship in order to trade with them for supplies. (TNG - The Dominion War novel: Tunnel Through the Stars)