A palio was an annual athletic contest, often pitting neighboring species and cultures against each other.
Deep Space 3 hosted the 2370 palio, and the Ferengi were accused of trying to bribe a Breen pilot into throwing the race. (TNG: "Interface")
During the Middle Ages on Earth, palios often involved horse racing, archery, jousting, and similar medieval sports. It is unclear what kinds of events palios in the 24th century involved.