During the 14th Dynasty (Second Intermediate period) there were very many minor kings in Egypt, probably none of whom ruled the entire country. Their names and titles are known only from scarabs inscribed with their cartouches.
Ya'ammu and Nubwoserre may have been two different people, or two names belonging to the same king. The names date to anywhere between 1783 to 1640 BC, when the 13th, 14th and 15th (Hyksos) Dynasties ran at the same time, indicating a period of upheaval, confusion and internal power struggles.
19 very poorly-carved scarabs with the name Nubwoserre are known and 7 with the name Ya'ammu; with crudely cut scarabs it is possible that names are garbled and that some represent different writings deriving from one name.