Extreme and Flemish Revolution

I've been practicing against the extreme AI. I just played a black forest as vikings vs burgundians. I was able to wall off a choke and keep the AI at bay until imp. It got there first but didn't push with trebs. Instead, a mass of Coustillier and skirms flood my choke walls. Luckily, I had enough archers to utilize the choke. The AI units went down and as I regrouped, the AI resigned. It through me off guard because the AI hasn't been resigning for me until about a 10-15 thousand score difference, but this was only 7000 difference. I looked over the map and realized it had no eco because it went for the Flemish Revolution 11