 The Riders' names for the cunningly-built tower of Isengard, Orthanc, and for the Ents, the tree-giants of Fangorn forest, are similarly Old English, both being found in the phrase "orþanc enta geweorc", "the work of cunning giants" in the poem "The Ruin", though Shippey suggests that Tolkien may have chosen to read the phrase also as "Orthanc, the Ent's fortress".In "The Two Towers", chapter 6, the Riders of Rohan are introduced before they are seen, by Aragorn, who chants in the language of the Rohirrim words "in a slow tongue unknown to the Elf and the Dwarf", a "lai" that Legolas senses "is laden with the sadness of Mortal Men".The song is called the "Lament of the Rohirrim".