Detailed Instructions: You are given a passage. You need to construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) its answer is the whole paragraph. Avoid creating questions that can be answered correctly without actually understanding the paragraph.
Q: The earliest form of currency used was large stones that could be used to get food and meat in exchange - this was during the stone age. Before this there was a barter of goods (so i am not considering it currency)
Large stones which were round were considered more valuable since they were more difficult to obtain

The first recorded accounts of currency date back to 2000 BCE and silver or metal tokens were used to represent a stored value of grain. Also these were useful to ensure that a shipment of commodities arrived with the same goods that were shipped

Paper money was used in the 18th century, but only in the late 18th and through the 19th century was a central monetary authority created in various states that had a virtual monopoly of creating bank-notes that had to be accepted as legal tender everywhere (Prior to this, the one accepting payments could refuse the payment if it was not in a currency which had been predetermined before the loan or in general use: Note gold and silver were widely used as legal tender)
A:
What was the first currency ever used?