#Galatians
The letter addresses the early Christian communities in the Roman province of Galatia, in central Asia Minor, which is in modern-day Turkey.
Taken chiefly from Wikipedia: It would have been enormously helpful to Paul’s primary argument in his letter if he could have mentioned the decision of the Council of Jerusalem that Gentiles should not be circumcised. The absence of this argument from Paul strongly implies Galatians was written prior to the council. Since the council took place in 48–49 AD, and Paul evangelized South Galatia in 47–48 AD, the most plausible date for the writing of Galatians is 48 AD. This makes it among the earliest New-Testament writings