The name "Thorn Valley" originates from the children's fantasy story Mrs. Frisby and the Rats of NIMH, in which a group of several dozen rats have escaped from the laboratory in which their intelligence was enhanced to human-equivalent levels. They have acquired a great deal of human technology, but recognize that they are in an untenable situation as long as their quality-of-life depends on stealing equipment and supplies from humans.
They develop a plan to move their society to a location they call "Thorn Valley", far away from humans, trading the benefit of theft for the benefits of building their own technology (and thus having better control of it) as well as being free of the various threats posed by proximity to human society (typified by agricultural machinery, cats, and rodent extermination in general).
Note than in the movie version of the story, re-titled The Secret of NIMH, the rats use magic rather than engineering as the primary basis of their technology, and some of the primary characters are depicted as evil or twisted. In the book, the worst trait any significant character demonstrates is hubris, in believing that they can continue to steal technological matériele without really understanding how it works and hence the hazards involved. (Members of a splinter-group which wants to continue raiding human tech are electrocuted while trying to gnaw through a power-cable.)