Ok, so Beijing, my capitol, expanded to take this horse tile. A few turns after, the Arabs built a city right next to that horse tile. A few turns after that I went to war with the Arabs and took that city. I didn't want it, so I picked the option to raze it.
Somehow that horse tile was counted as belonging to that captured Arab city and when it finished razing, that tile was no longer within my territory!
Somehow that horse tile was counted as belonging to that captured Arab city and when it finished razing, that tile was no longer within my territory!