Here is an excellent paper that summarizes the relationship between the coinage of the Ptolemies and in-kind payments and rents. It is postulated that early in the Ptolemaic period most of the native population was accustomed to paying and receiving sums of money on an in-kind basis, with the mode of exchange typically being grain. However, during the reigns of the succeeding Ptolemies after Ptolemy I Soter bronze coinage was issued to form a uniform standard of exchange across the kingdom. Because of the rarity of silver in Egypt the Attic standard of the silver tetradrachm was eventually made more and more scarce to the point where it disappeared. Papyri from Oxyrynchus list prices paid for various transactions, including rents and contracts. It is noted that starting with the reigns of the succeeding Ptolemies Egypt was basically a closed economy and that the state was able to maintain values for taxation, common everyday transactions and rent payments based on the bronze coinage in large part. In the Roman period this closed economy persisted down to the year 296 when the follis was introduced and struck in large numbers in Alexandria during the reign of Diocletian who had instigated the monetary reforms. From this point Egypt lost its unique currency and was transferred to the Imperial standard, with free exchange of coins between the provinces which must have simplified trade. https://www.oxfordhandbooks.com/vie...99935390.001.0001/oxfordhb-9780199935390-e-71 AE of Ptolemy IV Philopator Billon Tetradrachm of Diocletian, the last native coinage.
I also have had the opportunity to research papyri first hand using my knowledge of the ancient script, in particular the papyri originating in Tebtunis, Egypt as I am a financial supporter of the Berkeley Tebtunis project. http://www.lib.berkeley.edu/libraries/bancroft-library/tebtunis-papyri Tebtunis, in the Fayyum, was a site of a temple dedicated to Sobek, the crocodile god.
Amazing! Why was silver so much more rare in Egypt than in other parts of the ancient world? Was all the silver sucked into Rome itself? An Egyptian AE drachm and an octobol (at 46 mm my largest coin) on a piece of original papyrus.