This name also coincides with that of the Seneca, a Native American tribe that lived near the Great Lakes, whose name meant "place of stones".
As an English name, it became popular due to the Fleetwood Mac song Rhiannon (1976), especially in the United Kingdom and Australia.
This name was fairly common in France, England and the United States in the early 20th century. It became quite popular in France and England at the end of the 20th century, just when it was at a low point in the United States. It quickly climbed the American charts and entered the top ten in 2014.
As a given name, it was used on the American sitcom Murphy Brown (1988-1998) for both the mother and son of the main character. By 1998 it was more popular as a name for girls in the United States, perhaps further inspired by a character from the movie Jerry Maguire (1996).