The Dunes of Talmouth were a geographical feature.
Neelix's sister Alixia once mounted an expedition to the Dunes of Talmouth. One of Neelix's most prized possessions was a necklace she made during that trip. (VOY: "Mortal Coil")
The Dunes of Talmouth were named by Bryan Fuller. He invented the name "Talmouth" after the honorific Hebrew title "Talmid". (
Information from Larry Nemecek)