Why not you upload your record game on the Great Plains? You have used the benefit of limited AI of the Age of Empires III.
They have thrice or more land and naval army but they are not attacking since they have destroyed your first town center and are limited not to attack on the isolated island where you have shifted your base. There are many this-type maps. :D:D:D
Please try fighting on map with no waters. :)
Waiting for your next recorded game on land.