The Almighty dF
Pharaoh
Well, right now, we got an European civ, a Middle Eastern Civ, an American civ, and a Pacific Civ.
Let's think of Asian civs. Tibet is a good choice. But we'd need a Dalai Lama LH.
Another choice would be the Chola or Tamil Civ, with Rajendra Chola as leader.
Kazakhstan and Uzbekistan have also been proposed.
Now for Africa... There are actually big empires you could choose. The Ashanti (led by Osei Tutu, and if you want to expand it to modern day, Kwame Nkhrumah or Kofi Annan-would make the diplomatic victory make sense!), the Swahili (led by Barghash) and the Mutapa (led by Mutota and perhaps Robert Mugabe).
And of course, there's always South Africa. Let's face it, with Mandela where he is, we got a Xhosa hanging out with the Zulus. And Zulus don't like Xhosas. So it would be a good choice to pair him up with Paul Kruger and make SA.
Seconding Tibet. Dalai Lama LH would be extremely easy to make if it doesn't exist.
I'd love to see Libya in-game... but if I had to pick a different civ to suggest... hmm...
I'd suggest Lao but that region is already covered very well.
Bah. It's hard to think up some suggestions for African civs. We've pretty much covered everyone that matters.
Sudan maybe?
Or Kenya.