The Cherons are a race based on racial prejudices. They have the skin colored half black and half white. Cherons with left side white are the masters, and Cherons with left side black are slaves. Since their strenghts are equivalent they can never beat each other. When Enterprise did first meet Cherons (Stardate 5730.2) Bele (the master) has chased Lokai (the slave) for 50.000 years.
Referring episode : Let that be your last battlefield