What is money?
Money is anything that we mutually agree to use to facilitate a business transaction, where the providing party of goods or services requires acknowledgement and an agreement from the receiving party, that a debt will be repaid or reciprocal action performed at some in the future. The facilitating instrument is determined by the parties and is usually transferable.
More importantly, money is created only when a transaction occurs. Before that, money does not exist.
If this definition of money is accurate, the method for honoring the promise relating to the transaction is the money, not the currency.
We have confused our access to accepted means of exchange (world currencies) with what money actually is.
While we experience ease or difficulties in transacting businesses, based on the amounts of currency available to us, it is we that create money, not our access to currency.
Providing there is a means for acknowledging and recording the debt created; That a known currency may not be available to you at the time, should not prohibit you from conducting a business transaction,
For such B2B transactions, "CityC" is that currency.