they claimed that without slaves the economy would collapse I think, I'm not quite sure if I'm remembering correctly though
He confirmed the papacy in possession of Ravenna and the Pentapolis, the so-called Donation of Pepin, whereby the Papal States were established and the temporal reign of the papacy officially began.
It freed the serfs who had been bound on the land for 10 or more years
Answer:
The mining of Iron and Gold.
Explanation: