How the Roman empire of the first century was created
The Greco-Roman Commonwealth came to an end with the great world catastrophe which I date in about 1350. From the chaos emerged new political structures. Parts of the Commonwealth became the private property of kings, dukes, counts. The papal institutions reflect the original presidency of the Commonwealth.
"Imperatores", that means military commanders, became "emperors" in the sense of a head of state or of a new kind of commmonwealth. And so we had the Holy Roman Empire in the West, and a shortliving Greek empire in Constantinople.
Christanity was created in that time. The makers of history placed the origin of Christianity back to the time that became the first century.
http://jefdemolder.blogspot.com/2019/07/how-roman-empire-of-fir