Sennar is geographically part of what is now #Sudan. The history of the Sudan seems to be one of conflict with the sultanate of Sennar providing some continuity for over three centuries.
When you read about it, Sennar was a backwater and this allowed it to develop its own culture which was distinct. As so few people are interested in this culture, these people you will not find much information in Wikipedia.
The information you do find of the Sennar sultans in the English Wikipedia is problematic when you want to enter the data in Wikidata. The problem is not only that there is no article for many sultans, the biggest problem is with the dates.
The date when the reign of Amara Dungas ended is given as AH 940. This date is provided in the Arabic calendar and as the illustration indicates, this is either 1533 or 1534 AC.
Technically an acceptable solution is not that hard; when it is possible to say 1533s, meaning it can be up to one year earlier or later it would already be a big improvement. A proper solution means that dates can be entered in the original calendar. This is a lot more complicated but it will allow people to enter more accurate information.