Hakama (袴) are a type of traditional Japanese clothing. Trousers were used by the Chinese imperial court in the Sui and Tang dynasties, and this style was adopted by the Japanese in the form of hakama beginning in the sixth century. Hakama are tied at the waist and fall approximately to the ankles. They are worn over a kimono (hakamashita). There are two types of hakama, divided umanori (馬乗り, literally horse-riding hakama) and undivided andon bakama (行灯袴, lit., lantern hakama). The umanori type have divided legs, similar to trousers. Both these types appear similar. A "mountain" or "field" type of umanori hakama was traditionally worn by field or forest workers. They are looser in the waist and narrower in the leg. Hakama are secured by four straps (himo): two longer himo attached on either side of the front of the garment, and two shorter himo attached on either side of the rear. The rear of the garment has a rigid trapezoidal section, called a koshi-ita (腰板). Below that on the inside is a hakama-dome (袴止め) (a spoon-shaped component sometimes referred to as a hera) which is tucked into the obi or himo at the rear, and helps to keep the hakama in place. Hakama have seven deep pleats, two on the back and five on the front. The pleats are said to represent the seven virtues of bushido, considered essential to the samurai way. Although they appear balanced, the arrangement of the front pleats (three to the right, two to the left) is asymmetrical, and as such is an example of asymmetry in Japanese aesthetics.