Xiǎolóngbāo, also known as soup dumpling, is a type of baozi from eastern China, including Shanghai and Wuxi. It is traditionally steamed in small bamboo baskets, hence the name (xiaolong is literally "small steaming basket").
Xiaolongbao are more often known in Shanghai and its surrounding areas as xiaolong mantou (simplified Chinese: 小笼馒头; traditional Chinese: 小籠饅頭; pinyin: xiǎolóng mántóu). Mantou describes both filled and unfilled buns in southern China, but only describes unfilled buns in northern China. To avoid confusion, the name xiaolongbao is usually used in other areas.
Xiaolongbao in Wuxi tend to be sweeter and have a thinner dough skin, and are juicier than the Shanghai variety.