Ok
Im playing China and had no horses for the Riders. Now I traded, and got horses. I even renegotiated for another 20 turns
until they attacked me on turn 12. Now, I cant seem to upgrade my Riders to Cavalry. Do you need to have the resource to upgrade an existing unit?
(I rushed to Military Tradition just to find out I can't upgrade... what a waste of time!
)

(I rushed to Military Tradition just to find out I can't upgrade... what a waste of time!
