I have read that this design was created to emulate jade rings that symbolize eternal life, in the same way spade coins and knife coins emulated spade and knife tools, respectively. The round hole served no real purpose other than to facilitate stringing the coins together. The inscription on the obverse says "Yuan," which was a city in the ancient state of Liang, not the monetary donomination. This variety is by far the most common, and all other types are incredibly hard to obtain. While I have no written provenance, I presume that it was one of 1180 "Yuan" coins unearthed from a 1981 hoard in the Henan province of Modern-Day China. Its patina matches several I have seen for sale, and you can see the imprint of another coin on the reverse, which shows that it was buried between other coins. (Usually the imprint of another coin on a coin in question is a sign of authenticity, but I have seen counterfeits that display this feature, though it looks more like a vice job than a transfer of patina.) The round-hole coins are a product exclusively from the states that produces spade coins during the Warring States period. During this era, there were two monetary systems in China, one based on spades and one based on knives. The two types circulated contemporarily, and there was little overlap, with the only exception coming to mind being the city of Lin. The coins with the square holes came from the states that used knives exclusively. However, as the kingdom of Qin grew in power (a spade state), they started casting coins with square holes known as Ban Liangs. These were produced in such industrial quantities that a square hole was needed to make an efficient filing process. But more on that later.