Hanfu refers to the traditional styles of Chinese clothing worn by the Han Chinese since the 2nd century. Several distinct garment systems sit under the term. The ruqun pairs an upper-body garment with a long outer skirt, and the aoqun pairs one with a long underskirt. The shanku combines an upper-body garment with ku trousers. The beizi is a loose outer coat with long, loose sleeves. The shenyi is a robe with straight plackets and overlapping collars.