Dynasty Period Years 1-2 Early Dynastic 3100-2686 BCE 3-6 Old Kingdom 2686-2181 BCE 7-10 First Intermediate 2181-2133 BCE 11-12 Middle Kingdom 2133-1786 BCE 13-17 Second Intermediate 1786-1567 BCE 18-20 New Kingdom 1567-1080 BCE 21-25 Late New Kingdom 1080-664 BCE 26 Sait 664-525 BCE 27-31 Late 525-332 BCE Ptolemaic 332-30 BCE Roman 30 BCE - 642 CE Arab 642 CE to present time
Many people have speculated on the purpose of the pyramids down the ages. The Greeks, and later the Romans, thought that they were Royal Tombs, and this theory persists to this day among classical Egyptologists. The Royal Tomb theory does not, however, stand up to scrutiny, especially in the light of evidence provided by astronomy.