You are absolutely right. The explanation is simple though. There aren't obvious much or any members with your factual knowledge about the caliphate.
Surely. However, the issue could be greatly assuaged by way of people supporting timelines that are not explicitly European or European diaspora(s). There are many who make great calls: 'we require more diverse timelines, we need to see timelines on so and so and expand the boards existing corpus.' Yet, these same people or generally those who agree to these calls, neglect to support, provide assistance and give feedback on those timelines that do attempt at the utmost to expand the base of the forum. This is my issue and it has been an issue for the past five years and surely longer.
Mind you, I am no person to critique European history or what have you, and my record on the forum attests to this. Further, there are a great many posters on this forum in the Before 1900 that have skills in a large number of fields and write upon these topics in timelines. There is supplemented by a lack of knowledge thus, also a caution or lack of interest in said venues of history.