trade with barbarians!

[Gammaray fan]

Firaxis have for a fact said that barbarians will have cities, but I'm not sure if they have said that you can trade with them.
Since barbarians represent Celts (and possibly Viking if they aren't a civ) in Europe, Mongols (if they aren't a civ) in Asia, Natives in America, Australia, and SE Asia, and natives in Africa, it would make sense if you could trade with them and colonise them (through diplomacy agreements like 'give me 10 gold per turn + all your trade goods for our goodwill).

EFFECTS:
1. Zulus can fight historically and conquer barbarians to the north (thus eliminating ridiculous civ1 situation where Zulus built cities all over Africa and were challenging Europe in BC!)

2. Aztecs will have their hands full fighting trading with barbarian cities thus preventing 'perfectionist paradise' in America.

3. Europe can attempt to colonise barbarians in America (assuming they beat Aztecs), and gain luxuries galore to simulate their propulsion to world power status on the back of their colonies.

4. SE Asian islands can be colonised by any leading power (Japanese colonised Taiwan).

[Gammaray fan]

Additionally, Barbarians should just be civs that cannot research anything (but they can steal!), can only be dealt with on a city to city basis (no barbarian empire), and cannot build roads, mines, irrigation.

[AzNtoccata]

I think they should be self-contained empires within a city. THe research "cost" is less for them, but they still advance slowly...slowly...slowly. They should also build stuff faster.