You can claim as much land you want, it's just less densely populated. Say 1 city is 6 square miles and has 30,000 people, and another is 50 square miles and had 30,000 people. City 1 has less land, do the people are more densely packed, while in city 2 thy got a lot more space. If yu want more land just ask (also I would try to claim Syria/Iraq before Islamibomb does)