This article describes mainly the traditional Asiatic composite bow, which normally uses horn on the belly and sinew on the back of a wooden core. Sinew and horn will store more energy than wood for the same length of bow. The strength can be made similar to that of all-wood bows, with similar draw-length and therefore a similar or greater amount of energy delivered to the arrow from a much shorter bow. Some Mongolian composite bows are known to have been able to produce a draw weight of nearly 160 lb (72.5 Kg).
The main advantage of composite bows over self bows (made from a single piece of wood) is their combination of smaller size with high power. They are therefore much more suitable for use from horseback, and presumably from a chariot. Almost all composite bows are also recurve bows as the shape curves back away from the archer; this design gives higher draw-weight in the early stages of the archer's draw, so storing somewhat more total energy for a given final draw-weight. It would be possible to make a bow of wood that has the same shape, length and draw-weight as a traditional composite bow, but it could not store the energy and would break at full draw.
Constructing composite bows requires much more time and a greater variety of materials than self bows, and the animal glue traditionally used can lose strength in humid conditions and be quickly ruined by submersion. For most practical non-mounted archery purposes, composite construction offers no advantage; "the initial velocity is about the same for all types of bow... within certain limits, the design parameters... appear to be less important than is often claimed." However, they are superior for horsemen and in the specialized art of flight archery: "A combination of many technical factors made the composite flight bow better for flight shooting."
The wooden core is not normally under severe mechanical stress, and a wide variety of lighter woods should be suitable. The wood needs to accept glue well. Bamboo and wood of the mulberry family are traditional in China.
The sinew is normally obtained from the lower legs and back of wild deer or domestic ungulates. Traditionally, ox tendons are considered inferior to wild-game sinews since they have a higher fat content, leading to spoilage.
Other less-satisfactory materials than horn have been used for the belly of the bow (the part facing the archer when shooting), including bone, antler, or compression resistant woods such as osage orange, hornbeam, or yew. Materials that are strong under tension, such as silk, or tough wood like hickory, have been used on the back of the bow (the part facing away from the archer when shooting).
The first appearance of composite bows coincides approximately with the adoption of the horse to draw chariots or as a riding animal. Variants of the Scythian bow were the dominant form for millennia in the area between China and Europe. These were short weapons - one was 119 cm long when strung, with arrows perhaps 50-60 cm long - with working tips. Composite bows were soon adopted and adapted by civilizations, such as the Chinese, Assyrian, Indian, and Egyptian, who came into contact with nomads. Several composite bows were found in the tomb of Tutankhamun, who died in 1324 BCE. Composite bows are known in China from at least the Warring States Period. The military of the Han Dynasty (220 BCE-206 CE) utilized composite crossbows, often in infantry square formations, in their many engagements against the Xiongnu. Horse archers such as the Scythians, Parthians, Huns, Bulgars, Seljuk Turks, and Mongols often used skirmishing tactics where they would approach, shoot, and retreat. The term Parthian shot refers to the widespread horse-archer tactic of shooting backwards over the rear of their horses as they retreated.
Aryan nomads such as Scythians, Sakas, and Sarmatians were skilled horse archers. Parthians, originally a Scythian tribe, were famed horse archers. Parthians inflicted several devastating defeats on Romans, the first being the Battle of Carrhae. However, horse archers were not invincible; Han General Ban Chao led successful military expeditions against these nomads in the late 1st century CE that conquered as far as central Asia, and Alexander the Great may be the only general who inflicted a defeat on horse archer armies on his first contact with them.
With the arrival of the Huns, a separate tradition of bows with siyahs arrived in Europe. "Rausing termed it the 'Qum-Darya Bow' from the Han Chinese type-site at the frontier post of Lou-lan, at the mouth of the (Qum-Darya) river, dated by analogy to c. 1st century B.C. to 3rd century A.D. Fittings from this type of bow appear right across Asia from Korea to the Crimea. Alanic graves in the Volga region dating to the 3rd to 4th century A.D. signal the adoption of the Qum-Darya type by Sarmatian peoples from Hunnic groups advancing from the East. In general, Hunnic/Qum-Darya bows had two pairs of ear laths identical in every respect to those found on Roman limes sites. The only difference is that there are proportionally a greater number of longer laths (like those Roman examples from Bar Hill and London). In addition the grip of the bow was stiffened by three laths. On the sides were glued a pair of trapezoidal laths with their longest edges towards the back. On the belly was glued a third lath, varying in shape but often narrow with parallel sides and splayed ends. Therefore, each bow possessed seven grip and ear laths, compared with none on the Scythian and Sarmatian bows and four (ear) laths on the Yrzi bow.
Such bows may usually have been asymmetric, with lower limbs shorter than the upper. To some extent, this combines the power of a longer bow with the convenience of a shorter one.
The Huns and their successors greatly impressed their neighbours with their archery. Germanic tribes transmitted their respect orally for a millennium; in the Scandinavian Hervarar saga, the Geatish king Gizur taunts the Huns and says, "Eigi gera Húnar oss felmtraða né hornbogar yðrir." (We fear neither the Huns nor their hornbows.) The Romans were so impressed with Hunnic tactics that, as described in the Strategikon, Procopius's histories, and other works, they changed the entire emphasis of their army, from heavy infantry to cavalry, many of them armed with bows.
After the fall of the Western empire, Eastern Roman armies maintained their tradition of horse archery for centuries. They finally fell to the Turks before the decline of military archery in favour of guns. Turkish armies included archers until about 1591 (they played a major role in the Battle of Lepanto (1571), though they were defeated by the firearms-wielding Christians), and flight archery remained a popular sport in Istanbul until the early 1800s.
Most surviving documentation of the use and construction of composite bows comes from China and the Middle East; until reforms early in the 20th century, skill with the composite bow was an essential part of the qualification for officers in the Chinese Imperial army.
The Chinese archery tradition goes back millennia. There is also a long tradition of local developments. The modern Chinese and Mongolian bows are similar to each other, both having string bridges derived from the Manchurian tradition.