T.S. Eliot had an unbelievable memory, and he read an amazing amount of books. He also had a habit of trying to guess where he had come up with lines and titles by remembering things he had read that contained similar expressions. For this poem, he claimed to have combined the title of a poem by Rudyard Kipling (of The Jungle Book fame), "The Broken Men," with the title of story by a writer named William Morris, "The Hollow Land." He claimed, "I combined the two" (source).
To be honest, we don't think that Eliot's memory adventures are necessarily useful when reading his poems. A more important connection might be Marlow 's description of the character Kurtz in Joseph Conrad's novella Heart of Darkness as "hollow at the core." This connection is relevant because the first epigraph of the poem is a quote from Heart of Darkness announcing Kurtz's death.
Even without the title, you would know that the Hollow Men narrate this poem from the first line.