Horseracing in Okinawa started in mid 18th century and ended just before World War II (or Battle of Okinawa).
It's called "horseracing" but far from the normal horseracing where thoroughbreds run fast to be the fastest horse and win the first prize.
In Okinawa Horseracing, two horses of the local breed (small-sized horses) run slowly to compete their beauty/ gracefulness in running. No prize, no betting by the public, but people gathered to see the horses run gracefully and had a good day. From the old map of Okinawa, we can see that there were 198 horseracing sites in Okinawa in mid 18th century. Those places are now parks, roads, or runways of US base in Okinawa.
Just like Sumo (Japanese Sumo Wrestling) they decided the pairs (which horse to run with which horse) and started with the lowest grade and up to the highest grade, to see the Champion of the year.
There was a superstar named "Hikooki" (meaning "airplane") who was white--very rare for the local horse then. (Most of them were light brown or brown.)