Size matters and a Google search found some help (in square kilometres):

1) Mali 1240
2) Northern Mali 827
3) Texas 692
4) Afghanistan 647
5) Iraq 438

The OECD has a short summary on Northern Mali:http://www.oecd.org/swac/northernmaliataglance.htm

If northern Mali were to become a state, it would be twice the size of Germany but with 1.6 residents per square kilometre. It would share with Mongolia the title of the country with the lowest population density in the world.