The only proof of the existence of a king!
The proof is on this extremely rare tetradrachm of Bastareos from Kingdom of Paeonia, c. 400 BC. Bastareos is known only from the three examples of this coin in existence today. Given that this coin was found with issues of two other Paeonian kings (Lykkeios and Patraos), it is assumed that Bastareos was a Paeonian king as well, or perhaps the king of a neighboring tribe, whose existence is otherwise unknown to history. This coin is of immense historical significance as there is no other proof that Bastareos ever existed.
On the coin is a large crested helmet in a border of dots. The reverse shows the inscription of BAΣTAPEOΣ over a bull butting to the right on the ground all within a border of dots.
The ancient Kingdom of Paeonia was located in Thrace (modern northern Greece, the Republic of Macedonia and a part of Bulgaria & Kosovo).