In Anushasana Parva (165), Bhishma tells Yudhishthira about the names of the deities, Rishis and Kings to be duly recited for efficacious cleansing of all sins. The following is the (abbreviated) quote for the names of kings :
After this I shall recite the names of the principal kings. They are Nriga, Yayati, Nahusha, Yadu, Puru of great energy, Sagara, Dhundhumara, Dilipa of great prowess, Krisaswa, Yauvanaswa, Chitraswa, Satyavat, Dushmanta, Bharata who became an illustrious Emperor over many kings, Yavana, Janaka, Dhrishtaratha, Raghu, that foremost of kings, Dasaratha, the heroic Rama, that slayer of Rakshasas, Sasavindu. ...
Yavana in ancient India was used for a particular tribe/kingdom/janpada lying to the west of Aryavarta, usually identified with Ionians. The only instance that I'm aware of it being used as a name of a king is Kalayavana, which doesn't appear to be the case here, since Kalayavana has been associated with Danavas and portrayed in a negative light in the Shanti Parva as attacking Dwarka.
So, who is the king Yavana mentioned here?