The Liu-Song dynasty 劉宋 (420-479) was the first of the Southern Dynasties 南朝 (420~589). It was founded by Liu Yu 劉裕, known as Emperor Wu 梁武帝 (r. 502-549), who was a famous poet and patron of Buddhism.
Source: Yang Debing 楊德炳 (1992). "Liang 梁", in: Zhongguo da baike quanshu 中國大百科全書, Zhongguo lishi 中國歷史, vol. 2, pp. 574-576. Beijing/Shanghai: Zhongguo da baike quanshu chubanshe.