Rome’s claimed descent from deities, and might have kinda been telling the truth if you follow the theory that polytheism starts as ancestor worship.

Claiming descent from deities was common in Rome. The justification for the inheritance of autocracy was, theoretically, the grant of power by the Senate in the name of the people of Rome (in practice, the support of the elite or the military), and the dual fact that actual hereditary inheritance was fairly rare and that ruling families changed as often as fashion means that descent was not the primary justification.

The Roman Empire was inaugurated by Augustus “just happening” to hold several very powerful titles of office simultaneously, and never giving any of them up and passing them all on to his chosen successor. It’s actually pretty funny just how bureaucratic his takeover was considering how many stoic statues of him in military attire there are. Guy became the king of the Mediterranean through paperworking his way into it.

Paperwork wins empires, it would seem. And propaganda. Lots of propaganda work from Augustus.