A Princess of Mars
On March 4, 1912, Burrough's editor at "All-Story Magazine", Newell Metcalf, wrote suggesting a sequel to "Under the Moons of Mars" (the original title of "A Princess of Mars"). The Valley of Dor, the River Iss and the Sea of Korus were all key locations in the Martian conception of heaven or the afterlife, which Burroughs had introduced in "A Princess of Mars". Metcalf, who thought the appeal of these mystical locations might be strong for readers of the previous tale, suggested that John Carter could arrive from Earth at this location and be instrumental in exposing and destroying this religion as a falsehood. These ideas, which may have already occurred to Burroughs, appeared to be highly inspirational.