A resistance has existed in some shape or form in Yraldrig since its rule was taken over by humans and subsequently robbed half-elves, half-orcs and tieflings of their autonomy. It hasn't always been organised, however, and at the beginning it was comprised by small separate groups or single individuals who would attempt to either kill people in power or free half-elves, half-orcs and tieflings from bad situations and get them across borders to other countries.
The resistance has code words and certain markings or items on their person to recognise each other without having met before. Especially human members are required to wear a crescent moon somewhere visible on their person and three ribbons in the colours red, green and blue.
A standard greeting goes as follows:
Person 1 - "I wish you peace."
Person 2 - "With all obstacles cleared."
Often the greeting is spoken in elvish and quietly so no non-resistance members can overhear.
The larger more organised resistance was established around the year 1900 of the Age of Awakening when the royal family of Eischland slowly started sending over spies to assess the situation and help where they could. Even though the urge to help as many as they could immediately, they've deliberately kept the process slow as to not rouse suspicion, and in order to gain enough information about high standing members of Yraldrigan society so they would eventually be able to dismantle it from the inside.
Some spies have the specific job to be as endearing as possible to whatever human families they serve so as to bring more humans to the realisation that the current treatment of the so called "half-breeds" is wrong and that the notion that they're less than people is a lie that they've grown up with. Most of the half-elves, half-orcs and tieflings born in Yraldrig also grow up with this lie which made it more difficult for them to break free of this notion without outside influence.
During the years spent active, the spies and other recruited members of the resistance have been able to clear most of the villages and towns close to borders of civilian half-elves, half-orcs and tieflings and replaced them with trained people. However, the vast majority of villages, towns and the capital city are far away from borders or along the coast and attempts to get people out of those settlements are dangerous and often end with death when attempted thanks to the even stronger military presence in those parts.