They can be quite annoying with they cavalry archers.

How I fight:
I have a large number of archers (7+) too to fight the horse units
I have the archers use the spear defence option
I put spearman on the sides (they always try to flank you)
try to make them shoot on my heavy armoured units (they can handle an arrow or 2)
I make sure terrain is on my side (defend hill tops)
Fight in the forrest and use horsemen to suprise attack them from the sides and take out they archers on foot

and off course.. if I can fight from a city who has cannons, its a piece of cake!