In the historical drama Palm Heart, Liu Shishi donned a Tang-style shirt paired with an outer vest, sparking discussions among netizens: Isn't this just a vest? And it can be worn outside? This outer garment, known as Beizi (背子), was a popular style in early Tang Dynasty. It came in various designs, including the Tanling (坦领, open-collar), Jiaoling (交领, crossed-collar), and Jixinling (鸡心领, sweetheart neckline). The Tanling design, in particular, resembles modern-day vests, typically worn over long-sleeved inner garments. Though both Beizi and Banbi (半臂, half-sleeved jacket) were outerwear, they differed in sleeve length. Beizi was sleeveless, while Banbi had half-length sleeves, hence the name. Historical records suggest Banbi predated Beizi, with Emperor Gaozu of Tang shortening the sleeves to create the latter. By the Song Dynasty, Beizi evolved into a more generalized term, Beizi (褙子), encompassing sleeveless, long-sleeved, and mid-length sleeve designs. It became a unisex garment, with men's versions featuring Panling (盘领, round collar) for military officials and Dui Jin (对襟, front-opening) or Jiaoling for scholars. Women's Beizi often had front-opening designs, as depicted in The Dream of the Capital (东京梦华录). This fusion of functionality and style made Beizi a practical choice for daily wear, much like Liu…...