Discussion thread for [D20:Longbow, Composite (Weapon)](http://www.birthright.net/brwiki/index.php/D20:Longbow, Composite (Weapon)). If you would like to add a comment, click the Post Reply button.
Obviously they’ve never tried using a longbow from horseback. 
Japanese Longbows can be used mounted as the lower limb is shorter than the upper limb which solves the issue of hitting the horse.
Look up Composite Bow on wikipedia or in other sources. They were devised primarily for mounted archery. The D&D distinction:
Short bows are small and weak self bows (single piece of wood).
Long bows are tall (5ft+) but stronger bows made for being on foot (and out of a single piece of wood).
Composite bows are much more powerful, built of laminate materials to generate more force in a smaller form factor, thus able to be fired from horseback.