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. Ptolemaic dynasty:  Their rule lasted for 275 years, from 305 to 30 BC.
i don't know