I found this interesting and entertaining video on the importance of Egypt on ancient Rome, especially as a conduit for trade (thus, a source of revenue), as well as a rich supply of Egyptian grains and other local products. Not mentioned in this fascinating video was that the Egyptian economy was a closed one (coins did not circulate into or out of Egypt.  Its coins, therefore, did not compete with circulating gold and silver coins from the rest of the Empire. According to Kenneth Harl, in