Changshan - men's traditional clothing in late imperial China

"A changshan (help·info) is a traditional Chinese dress worn by men. In function, it is considered the male equivalent of the women's cheongsam (qipao). It is also known as a changpao or dagua. It was often worn by men with a magua or "riding jacket". These types of dress were widely adopted beginning under the Manchu rulers of the Qing dynasty, who required that men in certain positions wear this style. - Wikipedia"