Tosu (Chinese: 多续; pinyin: Duōxù) is a possibly extinct Qiangic language of China which shows strong affiliations to both the Loloish languages and to Tangut, the language of the Western Xia. Yu (2012) classifies it as an Ersuic language, which belongs to the Qiangic branch. There are "almost no Tosu speakers left", or "practically" no Ersu speakers left.