The key to Hunnic success seems to lie in one particular detail whose significance has not been fully recognized. Both the Huns and the Scythians used the composite bow, but whereas Scythian bows measured about 80 centimeters in length, the few Hunnic bows found in graves are much larger, measuring between 130 and 160 centimeters. The point here, of course, is that size generates power. However, the maximum size of bow that a cavalryman can comfortably use is only about 100 centimeters. The bow was held out, upright, directly in front of the rider, so that a longer bow would bang into the horse’s neck or get caught up in the reins. But—and here is the answer to our question—Hunnic bows were asymmetric. The half below the handle was shorter than the half above, and it is this that allowed the longer bow to be used from horseback. It involved a tradeoff, of course. The longer bow was clumsier and its asymmetry called for adjustment in aim on the part of the archer. But the Huns’ asymmetric 130-centimeter bow generated considerably more hitting power than the Scythians’ symmetrical 80-centimeter counterpart: unlike the Scythians’, it could penetrate Sarmatian armor while keeping the archer at a safe distance and not impeding his horsemanship.

From Peter Heather’s The Fall of the Roman Empire: A New History, London: Pan Books, 2006 (first published in 2005), p. 156.