In his first-century work Germania, Tacitus describes rituals surrounding a deity by the name of Nerthus, a theonym that is etymologically ancestral to Old Norse Njörðr. However, the figure described by Tacitus is female. Based on this scholars have suggested a Proto-Germanic hermaphroditic deity or a gender aspectual pair (similar to Freyja and Freyr), identified the obscure Old Norse goddess name Njörun as a potential name for the otherwise unnamed goddess, and in some cases identified a potential reflex of a narrative about Njörðr and his sister-wife in Saxo Grammaticus's 12th-century work Gesta Danorum.
