arena (n.)

1620s, "place of combat," from Latin harena "place of combat, enclosed space in the middle of Roman amphitheaters," originally "sand, sandy place" (source also of Spanish arena, Italian rena, French arène "sand"), a word of uncertain origin, perhaps from Etruscan. The central stages of Roman amphitheaters were strewn with sand to soak up the blood. Figuratively, "scene of contest of any kind" is by 1814.