The Greek of the New Testament very clearly shows an innovative syntax for adnominal genitives, which become almost exclusively postnominal. In this context, the conditions emerge for the reanalysis of residual prenominal genitive forms as non-core arguments of the verb at the clausal level, i.e. for the rise of a new External Possession Construction. This syntactic reanalysis can, in turn, be argued to be a trigger for the syncretism between genitive and dative case characterizing later stages of Greek. In this contribution I compare the situation found in the New Testament with documents of Classical andPostclassical Greek, aiming to assess to what extent similar conditions held already at previous stages and in sociolinguistically comparable witnesses. I conclude that the External Possession Construction as such was already current at earlier stages of the language, but that the general syntactic conditions conspiring to favor its reanalysis first appear in Biblical Greek.