Wikipedia
Banbi (半臂, lit. "half arm") also known as Banxiu is an item of traditional Chinese attire. It is a form of waistcoat or outerwear that were worn over ruqun, and had half-length sleeves. The style of its collar varies but it can be secured at the front either with ties or a metal button. According to the Chinese records, banbi clothing style was invented from the short jacket that the Chinese wear. It was first designated as waistcoat for palace maid but the popularity soon reach amongst the commoners. It was recorded in the Book of Jin, when Emperor Ming of Wei met Yang Fu, the emperor himself was dressed in commoner's Banbi.
During Tang Dynasty, there was another form of Banbi or short sleeve waistcoat worn called Yihe Dang 裆. The sleeve covers around the shoulder area and there is no opening in the front or back. In order to wear it, people would have to tuck in, then out from the neck of the clothing. Generally, it's worn outside of a long sleeve shirt. In the "Legend of Huo Xiao Yu" that was written during Tang Dynasty, the main female character Huo Xiaoyu wear this style most of the time.
Other sources suggest that banbi was adopted from Central Asia during the Tang Dynasty through the Silk Road when cultural exchanges were frequent. And that it was also known as beizi during Tang Dynasty.
Image:Court Ladies of the Tang.jpg| Court Ladies of the Tang dressed in Banbi with scarfs wrapped around it Image:Tang Paintings of a Woman, Found in a tomb in desert of xinjiang.jpg|A painting of a lady during Tang Dynasty Image:Banbi+zhiduo+aoqun.jpg|A Ming Dynasty portrait illustrating a woman wearing Banbi Image:Mingbanbi.jpg|A Ming Dynasty portrait illustrating a woman wearing Banbi