Complex sentence: This valley is sometimes called the Forty Mile Desert, because no matter which route was taken along the California Trail (Carson River Route or Truckee River Route) the travelers would have to endure with no usable water.
Split into simpler sentences: This valley is sometimes called the Forty Mile Desert, from the era of the California Trail. No matter which route was taken along the California Trail (Carson route or Truckee route) the travelers would have to endure without usable water.