How long was the rule of the dynasty that was active when the Rosetta Stone was inscribed?
Ptolemaic dynasty The Ptolemaic dynasty (Ancient Greek: Πτολεμαῖοι , "Ptolemaioi"), sometimes also known as the Lagids or Lagidae (Ancient Greek: Λαγίδαι , "Lagidai", after Lagus, Ptolemy I's father), was a Macedonian Greek royal family, which ruled the Ptolemaic Kingdom in Egypt during the Hellenistic period. Their rule lasted for 275 years, from 305 to 30 BC. They were the last dynasty of ancient Egypt.
Late Period of ancient Egypt The Late Period of ancient Egypt refers to the last flowering of native Egyptian rulers after the Third Intermediate Period from the 26th Saite Dynasty into Achaemenid Persian conquests and ended with the conquest by Alexander the Great and establishment of the Ptolemaic Kingdom. It ran from 664 BC until 332 BC. With the Macedonian Greek conquest in the latter half of the 4th century BC, the age of Hellenistic Egypt began.