Egyptian chariots get a combat bonus for fighting in desert.
Wierdly, having lost large numbers of men in the campaign to chariots, I did some custom battles last night & had a single legion take down 2 units of chariot archers on medium difficulty, though I did start out with 2 & the first got mashed early in the battle.
Likewise, a roman cavalry unit easily beat chariots on medium but got slaughtered on very hard.