>>/40257/
> degradation of the state salary systems in highly centralised, autocratic state
That's the origin of feudalism, Rome's degeneration led to that. In the west it happened earlier, especially in the northern provinces, in the eastern half of the empire this went slower and wasn't entirely complete (thanks to trade, and the fact that those parts weren't piss poor shitholes like Europe was, so money circulation added some padding) but happened nevertheless.
This inheritance thing of kings is also the depends category. In Merovingian Frank state they only accepted Merovingian kings. In Hungary up to 1301 only Árpáds could be kings.
How about other feudalisms around the globe? The daimyo system in Japan. Or in China? Although it leads away from the topic at hand, and not really important.