The Sith usually live in a swarm of 20-30 in the forrest nearby the city of Kaol. Sometimes they kidnap people and take them back to their hive to devour. Zo, a young child that had wandered off from her parents Dalen and Zan'te, was taken by a Sith. A passing Dejah Thoris heard Zo scream and rescued her.
Dejah Thoris offered the Kaol jeddak, Kar Tith, to capture a Sith for him, so that his scientists could produce a venom that would kill the Sith. Kar Tith accepted the offer. Since then, the people of Kaol are much safer from the Sith than before.