I turned again to watch the ships. They were now but specks on the horizon. They plied their way northward. In the northern autumn they would return, to be refitted and supplied again in Schendi, and would then, a few weeks later, in the southern spring, ply their way southward. Schendi, located in the vicinity of the Gorean equator, somewhat south of it, provides the ships with a convenient base, from which they may conduct their affairs seasonally in both hemispheres. I was pleased that I had seen the ships. I could not have conceived of a more pleasant way in which to have made their acquaintance. I had seen the passing of the fleet of the black slavers of Schendi...
---Explorers of Gor, Ch6

A –small- slaving business is mentioned as having only 2 to 3 hundred girls in an open market (Ushafu)

"Is Uchafu an important slaver?" I asked.
"No," said Ulafi. "He usually handles no more than two or three hundred slaves in an open market."
---Ch5