In this article we discuss some of the crucial issues pertaining to the evolution and classification of Pontic Greek. In particular, we examine the extent to which Pontic Greek participated in the koineization process. In light of the Romeyka data (still spoken in North-East Turkey in the area traditionally known as Pontus), we present our cue-based (in the sense of Lightfoot 2002) reconstruction method (see also Willis 2011), which, according to Sitaridou’s (2014a/b) study of the Romeyka infinitive, has, so far, yielded a phylogeny advocating the Hellenistic Greek roots of Pontic Greek with ‘leap-frog’ contact with other Greek varieties during the medieval period. We test this further by presenting evidence from the negation system, which seems to confirm this thesis. Finally, we compare these findings with the ones stemming from a recent computational phylogenetic study based on microparameters (Guardiano et al. in press), and the results are shown to be compatible.