Legends of Acheron
The various tribes of beastmen are the results of an ancient wizard war some many years ago. The wizards at the time were skilled in mutagenics, or breeding magical hybrids. They swelled their armies with their creations and fought devastating wars, mainly north and east of Dalmasca. The wars have long past, and many of the wizards secrets died with them, although some wizards still specialize in creating chimeras. A few of the more hardy experiments and troops actually were viable breeds, and became inhabitants of the wilderness for the most part.
The wizards were fighting each other for the right to rule the world, so most beastmen were seen as evil, horrible, and destructive monsters by the other races. But enough time has passed that most beastmen (such as dogmen, bearfolk, and birdmen) are given the benefit of doubt by the other races. Except for goatmen and scorps of course, which are most generally considered totally evil in nature and should be exterminated.
Batkin: live in forests and deep caverns, very rarely seen. Notoriously ill tempered. Good as flying soldiers and muscle. Some batkin are tougher and stronger (double hp, plus to STR) and some have an extraordinary sonic attack.