An Egyptian priest named Manetho wrote a history of Egypt in Greek that divided everything into dynasties, a dynasty being various royal houses. In modern terms you have three Egyptian periods. Old, Middle and New Kingdom.
Early Dynastic Period: 3000-2600
Old Kingdom: 2600-2150 B.C
Middle Kingdom: 2000-1800
New Kingdom: 1550-1100 B.C
Late Period: 750 B.C - 1992 A.D or C.E in common terms.
Lower Egypt is Nile Delta, Upper Egypt is south of Delta
The Egyptian King was called "Lord of the Two Lands" and wore a double crown. Here! I'll even show you a picture of the three different crowns of Egypt.
Pretty neat, ja?