Encyclopedia Barsoomia Wiki
The information in this article comes from Marvels, warlord of mars and is not written by Edgar Rice Burroughs.

Roughly 1000 karads from Helium within a rift valley that is fifty miles wide and over 3000 miles long is the city of Karanthor. Here the live the True-Born. In ancient times the city was a global power, a city of scientists, the knowledge and might of the city rivaled that of the great city of Horz! A great cataclysm destroyed the city, and it was re-established within the great rift valley that opened near the now dead city!