Since the beginning of times, there had always been humans and animals. Over time, more species appeared on Earth. These species could not be classified as humans but at least, they could be identified as animals.
But then animals seemed a bit vague of a term to classify them as. Some were as harmless as domestic animals, others were left in the wild like wild animals but they didn't really fit into that term.
However, these strange species came to be termed as beasts. Though animals could also fall under the category of beasts, it felt more reasonable to point out exactly what these kind of creatures were.
Of these beasts on the Earth, time came and evolutions took place amongst them just like it did with animals. The evolution led to an upgrade amongst beasts that made a great number of them turn out to be the dangerous ones of the lot.
Some were seen as cursed and some had been sent into exile after being considered dangerous.