This is an extremely rare coin from Nikaia where only one other example is known. It’s uncertain when it is from. My opinion is it has all the hallmarks of a 4th or 3rd century coin, and I suspect it may come from shortly after it was captured by Lysimachos in 301 BCE.
However, the presence of some text or monogram below the butting bull may indicate a Roman consul’s name, and therefore put this coin in the 2nd century BCE. Since this example is in far better condition than the other one, it’s very difficult to say.
It is uncertain who founded Nikaia, but in 315 BCE it was captured by Antigonos Monophthalmos and renamed Antigoneia, the third such case I’ve found. In 301 BCE, after Antigonos‘ death, it was taken by Lysimachos and renamed Nikaia in honor of his recently deceased wife.
Since the city was only named Nikaia in 301 BCE, this coin cannot come from before then.
Antigonos Monophthalmos destroys the original city of Nikaia and renames it Antigoneia.
Antigoneia is captured by Lysimachos and renamed Nikaia, in honor of his recently deceased wife.
Nikaia comes under control of the Kingdom of Bithynia.
Nikaia, along with the rest of Bithynia, comes under Roman control.
Hadrian visits Nikaia after it’s damaged by an earthquake.
Council of Nicaea is convened by Constantine to address the Arian controversy. Athanasius, a key figure from Alexandria, emerges as a defender of orthodox Christianity against Arianism.