King Menes (also Meni) is considered as a unifier of Egypt according to tradition captured in Manetho's Egyptian sights on so-called Abydos King List and Turin King List. Perhaps he was identical with king Narmer, who was historically documented or with Aha (Hor-Aha). Menes chose Thinis (This, Tjenu) as his royal seat in Upper Egypt, which was situated about 500 kilometers to the south from Cairo.
Remains of this city hasn't been exactly identified yet. Menes sallied out to Lower Egypt and conquered it around the year 3000 BC. Then he established a new capital Memphis (Mennefer) on frontiers of both lands. It is possible, that there were attemps of unifying Egypt significantly earlier on the part of Lower Egypt rulers, who seated in On or Iunu (Heliopolis). But according to all preserved information, Menes was the first, who succeeded.
Menes (Narmer?) - Founder of the first dynasty
Menes is also considered as the founder of the first Egyptian kings dynasty, in all we know 7 or 8 of them. After Menes (or Narmer or Aha) the sources mention Djer, Djet, Den, Anedjib, Semerkhet and Qa'a. We know 10 kings from the second dynasty from Manetho and 2 others from other sources, but reliably documented are only 6 or 7 of them: Hotepsekhemwy, Raneb, Nynetjer, Weneg, Senedj, Khasekhemui and Khasekhemwy (perhaps 2 last are identical).
Briefly we can say, that they consolidated the state in political and also economical way; they waged offensive wars as well, especially on Sinai Peninsula because of copper mines and Nubia because of gold. It seems, that all of them had to subdue the separatist tendencies inside the land; Yet Khasekhemwy left a report about suppression of a big uprising in Lower Egypt.
The report said, that he killed 48205 (or 47209) rebels and took captive 120000 inhabitants. All of this made conditions for Old Kingdom origin, the oldest kingdom in history: it was almost a half Millenium older than Sargon's Akkadian Empire and almost one thousand years older than Hammurabi's Babylonia.