Ancient Uranium Bug?

[HeroicSpirit]

I was playing against Korea today on hotseat multiplayer in BNW and right around 900 AD, I saw that they had Uranium that they were willing to trade me. I was playing as Byzantium and I was doing pretty well against them. I had crossbows while they still had composite bows and showed no signs of any advanced technologies other than their mysterious Uranium. Now their city was strong enough to do about 80 damage to my catapult, but they still didn't seem especially more advanced than me.

Has anyone seen this happen before? The AI getting access to strategic resources they aren't supposed to have?

 

[mclericp]

could be that they aimed for nuclear fission and neglected machinery..???

Are their city buildings of the modern era? if so, that means they have discovered uranium. If not, it is a bug