Slavery was one of humanity's oldest trade, and the underground slave trade did not disappear in the technologically advanced Pan-Human Alliance territory. On the contrary, it was becoming a growing trend.
In the insectoid territory, which was in fair proximity to the Pan-Human Alliance, plenty of insectoid aristocrats or plutocrats would take pride in keeping human females in captivity. The Na'vi people also had a similar custom, except that they were a matriarchal race, so they preferred human males.
Driven by the profits to be had, many slave traders took the risk and expanded their business all across the universe, exchanging for minerals and creations needed by the Pan-Human Alliance from all the other territories.
