Polo is a small coastal city mentioned as the site of a famous boxing ring in My Monster Rancher. Because it seems that gambling on sports is a major pastime here, there is a chance that it could be the same coastal city where the Searchers first meet Captain Horn in Episode 15 of the anime series.
At the time, the coast of Bubalook Bay is deserted because the Zuums have taken control, but once Moo's rule ends, the area goes back to being pretty crowded.