The primary weapon of the Mongol forces was their composite bows made from laminated horn, wood, and sinew. The layer of horn is on the inner face as it resists compression, while the layer of sinew is on the outer face as it resists tension. Such bows, with minor variations, had been the main weapon of steppe herdsmen and steppe warriors for over two millennia; Mongols (and many of their subject peoples) were extremely skilled with them. Some were said to be able to hit a bird on the wing. Composite construction allows a powerful and relatively efficient bow to be made small enough that it can be used easily from horseback.