The duchies are often called "younger" (newer, more recent, etc.) in order to distinguish them from the older duchies which were vassal-states of the Merovingian monarchs.
Hertsogkondi kutsutakse sageli "nooremateks" (uuemateks, hilisemateks jne.) nende eristamiseks vanematest hertsogkondadest, mis olid Merovingi monarhide vasallriigid.