2. A group of adjoining mating territories of a species.
The Arena, More than a Place
The ancient Romans who watched the gladiators fighting to their deaths with swords and other weapons, or wild animals, killing and being killed, went to the amphitheaters for their "entertainment."
The ground couldn't soak up the quantities of blood spilled on it so the show producers covered the ground with absorbent arena (sand). The sand, or arena, became the name of the place for shows, then sports, etc.
The arena and areni- element is often heard but few know its origins; however, this list and the two arena parts will give you perspectives that will clarify how the word became a part of English: