Grassy Flatland.

And I suggest everyone should test it more...the more, the better. I know it's tedious (heck, I've planned to play as the Macedon until I encoutered this problem and then I stuck 2 whole day doing tests and making debates about it), but the truth will be out there only more tests are made. And if it IS a bug, then it's definetly a gamebreaking bug.

Seriously, I WISH I was wrong, but the more tests I did, the more depressing I feel. This bug, if exists (which is quite obvious IMO), really ruins many good cavalries and almost all barbarian factions (as their infantry need the charge bonus more than the more civilized factions).