Samuel Butler’s novel set in the anagrammatic country of Erewhon is Erewhon.
Published in 1872, the book’s full title is Erewhon: or, Over the Range. It is a satirical utopian novel in which the narrator, Higgs, crosses a remote mountain range and discovers a society with customs radically different from those of Victorian Britain. The name “Erewhon” is an anagram of “nowhere,” though Butler’s fictional country is also suggestively close to “now here.”
The opening journey draws heavily on Butler’s experiences in New Zealand, where he worked as a sheep farmer from 1860 to 1864. The book became especially influential for “The Book of the Machines,” a group of chapters imagining that machines might evolve, develop intelligence and eventually dominate humanity. This makes Erewhon an important precursor to modern science fiction as well as a satire of Victorian institutions.
The answer is sometimes confused with The Way of All Flesh, Butler’s semi-autobiographical novel, which was published posthumously in 1903. Erewhon also has a sequel, Erewhon Revisited, published in 1901.