Intriguing subject huh? It just so happened that playing as the Turks, one of my armies prepared to repell the Mongols was full of archers and just two heavy cavalry units while the Mongols had half of their fully stacked army composed of horse archers and the other half was heavy cavalry. Naturally nto good odds, so this strategy, while certain to sustain heavy losses, at least won me the battle.

Position your archers on as high of terrain as possible, of course, and put your cavalry on the flanks but a little bit away from the action. The enemy will more than likely head straight for the undefended archers. When the enemy hits your archers, circle around with whatever melee units you have and hit the enemy from the rear. You'll sacrifice most of your archer units but if you are unfortunate enough to be in this circumstance and unable to flee, it might be your only resort.

Ultimately I killed 1600 and lost 600, but again I did have a good terrain advantage.