In ancient Egyptian history, dynasties are series of rulers sharing a common origin. They are usually, but not always, traditionally divided into 32 pharaonic dynasties; these dynasties are commonly grouped by modern scholars into "kingdoms" and "intermediate periods". The first 30 divisions come from the 3rd century BC Egyptian priest Manetho, whose Aegyptaiaca, was probably written for a Greek-speaking Ptolemaic ruler of Egypt but survives only in fragments and summaries. The names of the last two, the short-lived 31st Dynasty and the longer-lasting Ptolemaic Dynasty, are later coinings.