First Japanese bows were made of single piece of wood and relatively short. By the III century B.C. the bows became longer (about 2 m) but they were still made of single piece of wood. Such bows were called “maruki-yumi”. The exact date of the first appearance of composite bows in Japan is unknown, however, the most ancient surviving Japanese bow is considered to be made during the V century A.D. During the Heian period (VIII-XII A.D.) the design of the bow became close to a modern one. Later on, the improvement of the design of yumi continued up to the Sengoku period. The Sengoku period yumi is considered to be nearly perfect, and its design and shape remain unchanged up to present days.
There are two types of a classicl yumi: long bow (daikyu) and short bow (hankyu). The length of daikyu depends on the archer’s height, but at any rate it exceeds two meters. Daikyu is the only bow which length exceeds the archer’s height. Daikyu has a rather unusual shape – it is assymetrical. It means that the bow’s grip is positioned not at the center of the bow, but at one third of distance from the bow’s lower end. There are several opinions on the origin of daikyu’s shape. The most popular explanation tells that the lower curve of the bow is smaller to facilitate shooting from horseback. However, the basic shape of the bow was established before horsemanship became widespread in Japan. There are two other explanations. First claims that asymmetrical shape allows to shoot while cneeling. The second is based on the early bows that were made from a single piece of wood. The curves of such bow were of different thickness and therefore their elasticity diffrerd too – asymmetry helps to deal with this. The hankyu’s design was similar to that of a daikyu, but it was (obviously) shorter and much less asymetrical as well.
Japanese used bows in warfare during their entire history (except the latest times, of course). Bow, and not some melee weapon, was considered the main weapon of early samurai. However, as time passed and tactics evolved, it lost its position to various swords and polearms. Nevertheless, bows remained in use even after the introduction of firearms in Japan.
Taken from the original website by ZVEZDA.
http://samurai-battles.com/historical-reference/japanese-bows/