Zardnaar
Legend
The problem with trying to completely genocide a group is not the issue of beating them in a war. In fact, most attempts to do genocide are done by a very powerful group against one that really has no power to fight back.
The problem is trying to track down and kill every last one of them. Orcs are really, really good at surviving in areas that other races would struggle to do. Furthermore, they breed far, FAR quicker than anyone else.
Compared to say Dwarves or Elves who can only really survive in a very comfortable range of climates (so much so that apparently Elves get all these subraces adapted to various climates that are insulated and don't ever cross-breed with any of the others for hundreds of thousands of years) and the fact that they take so very long to mature and even once they mature they don't make many babies or make babies very often....
Well, its a lot easier to wipe out the later than it is the former regardless of whether the former cannot possibly harm you.
No human has ever directly been killed by a Termite. Bears often kill people.
But if a group was determined to wipe out every last bear on earth, they would have no trouble doing it. If the group were to try to wipe out every last termite, they would fail.
Athasian Elves are different. It was also hinted that the Elves survived because the started running.
Orcs also lack spellcasters or arcane ones anyway. The wars lasted 1500 years and wrecked the planet. They would just have to kill them faster.
Athasian Trolls were also different more like intelligent cultured Ogres. Similar to the ancient giants.