Lo and behold the mystery that is the succesion question

This is how the appearance of the next King works:

You players by now should have realised that the best cavalry unit is often the unit where princes and especially Kings/Emperors/Khalifah/Sultan are in command of, therefore the province most likely to produce the best cavalry units with the best possbile upgrades will recieve the honour of the next sovereign appearing there.

Even if that province isn't able to produce those units which Kings and princes commands it is the province with the closent ability to produce them that wins the cake and slices it with his scimitar

Here's my experience, i made a new unit recently, this is the Klibanophori, a step above the Kats, when i had the ability to make these Klibs in Constantinople the Byz Emperors and their heirs switched to the Klibanophori units and appeared in Constantinople on the new succession because:
a] Constantinople could make the Klibs
b] Klibs are better than Kats