|The information in this article comes from Dynamites, Warriors of Mars and is not written by Edgar Rice Burroughs.|
The Thither are a mysterious race of giant red savages with four arms, enemies of the red men of Seth. They live in a hidden valley at Barsoom's south pole. They rarely venture into the world outside their valley because they are extremely fearfull and superstitious of outsiders. As a result, hardly any other race on Barsoom is aware of their existence.
The Thither are from Edwin Lester Linden Arnold's "Lieutenant Gullivar Jones: His Vacation" (more commonly known as Gulliver of Mars). This book predates Burroughs Martian series, but never achieved nearly the same popularity.