Complex sentence: The fantasy genre in the twentieth century grew out of nineteenth-century Romanticism, in which nineteenth-century scholars such as Andrew Lang and the Grimm brothers collected'fairy-stories' from folklore and in some cases retold them freely.
Split into simpler sentences: The fantasy genre in the twentieth century grew out of nineteenth-century Romanticism. Nineteenth-century scholars such as Andrew Lang and the Grimm brothers collected "fairy-stories" from popular folklore and in some cases retold them freely.