How can we make Tatars more viable?

As a cavalry archer civ, they aren't really good in maps like Arabia or in Arena, going by the statistics of the games.

My suggestion could be to implement one of the following:

1) Free Crossbowman

2) Free Ballistics

3) Cheaper Heavy Cavalry Archer Upgrade

4) Extend Silk Armor to All Cavalry

5) Make archer armour / attack-range line free in blacksmith.