the following 9th century (for example, depicted in a tapestry of the Oseberg ship burial). The problem with a breastcollar harness was that the actual shafts of the cart, chariot, or other vehicle are attached to a surcingle around the barrel of the horse. The breastplate primarily kept the surcingle from slipping back, not as the primary pushing object. This results in the horse literally pulling the load, a less efficient use of the animal. The modern breastcollar has traces which transfer the pull directly from the breastcollar, but a horse collar still is more effective for pulling heavy loads. China After the breastcollar harness, the next and final evolutionary stage was the collar harness. The collar allows a horse to use its full strength when pulling, essentially allowing the horse to push forward with its hindquarters into the collar. The fully developed collar harness was developed in Southern and Northern dynasties China during the 5th century AD. The first questionable depiction of it in art appears on painted moulded-bricks in the Three Kingdoms (220–265 AD) era tomb of Bao Sanniang at Zhaohua, Sichuan province, China. These paintings display an amply padded horse collar with no sign of a yoke. However, the earliest legitimate depiction of it in art is on a Dunhuang cave mural (cave 257) from the Chinese Northern Wei dynasty, the painting dated to 477–499 AD. In this painting the arching cross bar is clear, but the artist failed to clearly show the cushioned collar behind it, without which the whole design would have been rendered useless. The same basic design is seen in other painted Chinese frescoes, one from 520 to 524 AD (with shafts projecting beyond the horses chest for sternal traction), and another circa 600 AD (Sui dynasty). This Sui dynasty depiction (in cave 302) is of particular interest, since its depiction of the horse collar is not only more accurate (the same seen even in north and northwest China today), but it is used for a camel, not a horse. The Chinese had used camels often from the 2nd century BC onwards during the Han dynasty, and there was even a Camel Corps serving the military on the frontier of the Tarim Basin. However, the adapted horse collar for camels would not have been common until the 6th century. In cave 156, there is a panorama painting of the Tang dynasty Chinese general