Dynasties. Modern scholars divide the history of Egypt into thirty dynasties, following the practice of a third century B.C.E. historian named Manetho. He was an Egyptian who wrote in Greek for the Ptolemaic kings. His History of Egypt was meant to impress these Greek kings with the long and significant history of the country they now ruled. Manetho's book has not survived to modern times, but it was widely quoted by ancient authors. These quotes are the source for present-day knowledge of Manetho's writings. Manetho probably could read hieroglyphs and did research on the ancient king lists. His criteria for beginning and ending a dynasty, however, are not always clear to modern scholars. Sometimes a dynasty represents a change in family. The royal family of Dynasty 18 (circa 1539-1295/1292 B.C.E.), descendants of Ahmose, was not related to the family of Dynasty 19 (circa 1292-1190 B.C...