Kesef was a city on the Kyrian and Vaskan homeworld that was destroyed in the Great War between the Kyrians and the Vaskans. In the mid-31st century, the EMH backup module was unearthed beneath the ruins of Kesef. (VOY: "Living Witness") Kesef was named by Bryan Fuller. He took the name from a book about angels. (Information from Larry Nemecek)