The Felixus

It is believed that the Felixus population originated in the watched isles, but their history has no written record. Whether a record ever existed, or if it was scrubbed out by their rulers the result is the same.
The Yuan'ti of Anapat first record the use of Felixus slaves in 1322, around 200 years ago from modern day. Since this point, they have clearly built their society around the use of Felixus slave labour. The more agile and intellectual Felixus (Known as Tabaxi) are use for house hold slaves, servers and sometimes even scribes for copy. The less intellectual but strong slaves (Known as Leonin) are used for construction, dockhands and fighting for entertainment.
With the Felixus population outnumbering the Yuan'ti, the question of an inevitable uprising is often bought forward. In recent years, the Yuan'ti have solved this issue with their innate magical abilities and modern technologies. The "Collars of ownership" are powered by a central source in the capital of Atkon. Each one attaches around the neck of the slave and provides psychic damage when they are disobedient. 
There are 4 levels on the collar: Level 1 - For Felixus treated a servants. These only activate in extreme situation, such as attempting to kill a Yuan'ti. Level 2 - Rude acts towards Yuan'ti or attempted assault will activate the collar. Level 3 - Activated by refusal to work or speaking out of turn. Level 4 - No thoughts against the Yuan'ti are allowed. Note: At level 4, most Felixus reach a form of "Brain dead" where the brain simply obeys given instruction and becomes incapable of independent thought.
Collars are controlled by a small panel on their side that requires a personalised code from the owner. In some cases, they can also over a ranged controller if they think it is needed. 
The threat of higher levels is normally enough to discourage any disobedience. It is known that some Felixus have managed to escape but how is a different question.