Currenly playing as Russia. I have the Great Wall in Tiraspol, which has very helpfully kept the barbarians away from my cities. Around about 1400AD, a couple of barbarian horse archers spawned in Central Asia just east of the Urals. "Not to worry" I thought, as I have the great wall, and all my civilian units in the area are inside my borders, or will be before the barbarians reach them. But then, two turns later, they entered my borders near the (unguarded) city of Kzyl-Orda, and razed it to the ground. What gives? I can't see anything in the GW description to suggest it would have stopped working (unless "on continent" means that it won't work in Asia if built in Europe, but I thought "continent" in CIV just meant "landmass").