Where was Galatia and where were the Galatian churches located?
Galatia lay in Asia Minor, in what is now called Turkey, roughly down the middle of modern Turkey. The Galatian churches were probably in the southern half of that part of Turkey. These congregations had been established in Asia Minor and were being troubled by false teachers.
Les explains that Paul was frantically responding to false teaching that had come into the congregations he had established in Asia Minor, which is today called the land of Turkey. Galatia was located pretty much in the middle of what is now Turkey, and the Galatian churches were probably in the southern half of that part of Turkey. Those churches were being bombarded by false teachers claiming they could not be saved by faith and faith alone; they had to circumcise and keep the Law of Moses. Les notes a modern parallel: circumcision as such is not required, but other works in the same category do nothing but bring down God's anathema.