I'm not entirely sure it's useful to think about this part of the world in these terms during this time period. You're not dealing with proper nation states but, at the highest levels of organization, tribal confederations and hegemonies as well as the distinct religious leadership of the Ibadi sect of Islam. These controlled a fluid set of territories the population of which might shift wildly due to seasonal migrations of nomadic or semi-nomadic tribes. While the strongest of these groups in Oman secured their power with imposing forts, Muscat wouldn't really become a proper city and political power center until the arrival of the Portuguese.

Moreover, from what I understand this entire period for Oman is source poor. I've never come across population estimates for any part of the Arab Persian gulf before the modern era that are anything but incredibly tenuous estimates.