Kierion was an ancient city that was mentioned in Homer under the name Arne, and was at that time occupied by Boeotians. Shortly after the Trojan War, they were chased out by Thessalians.
The reverse depicts the nymph Arne, a daughter of Aeolos, who presumably founded the city, playing astralagoi, which may have been among the most ancient games we know. Although we don’t know the exact rules used back then, variations of the game continue to be played with rocks in the region. The idea is to throw one knucklebone up in the air and then try to pick up as many other knucklebones as possible before it falls.
In ancient times, the game was typically portrayed as being played by girls, as shown here, and young boys. We do have a Roman letter that describes some of the rules, from which we know that the sides of each knucklebone mattered. Tahberer speculates that they may have been used for divination.
Arne herself was born as a foal because her mother had been transformed into a horse (of course). Luckily, she was transformed back into a human. She then served as a nurse for Poseidon and even helped him out by denying where he was when Kronos came looking for him. Poseidon therefore fathered two sons, Aeolos (a different one from her father) and Boeotos.
Her ‘foster parent’ was enraged at her getting frisky with Poseidon (who at the time was a bull) and blinded her, then shut her in a tomb. He then placed her sons on top of a mountain to die. Luckily, her sons escaped and eventually freed her. She married a king and regained her sight, courtesy of Poseidon. Boeotos became the ancestor for the Boeotians.
From this coin, it’s clear that Kierion still valued their Boeotian heritage, even though we believe much of the populace was then Thessalian. What is unclear is the story of Arne with the astalagoi. Clearly there is a story here that we’ve lost. Was this how she spent her time while entombed? Perhaps Poseidon used them to trick her?