There's currently an exhaustive list and the list used in the 1st beta.
The list in the 1st beta is ancient civs only. This way I'm not accused of hating a certain country and its people or anything like that. I will likely shorten the exhaustive list for the final game after getting some suggestions of what to keep and what to lose.
Exhaustive list by time period
Egyptians
Romans
Greeks
Hebrews
Romans
Sumerians
Babylonians
Hitites
Babylonians
Assyrians
Greeks
Hebrews
Egyptians
Romans
Carthaginians
Celts
Sumerians
Franks
Vikings
Mongols
English
Kievan Rus
Arabs
Moors
Spanish
Holy Roman Empire
Portuguese
Swiss
Irish
Americans
English
Canadians
Mexicans
Russians
Chinese
Japanese
French
Israelis
India
Germans
Pakistanis
Italians
Turks
Egypt
South Africa
Iran
Iraq
Saudi Arabia
Indonesia
Australia
Austrians
Dutch
Incas
Aztecs
Mayans
Australian Aborigines
Sioux
Indians
Zulu
Abessinians
Javans
Songhas