1-2 Thessalonians are likely the earliest two letters of Paul we have in the Bible.
They were written in late 51 or early 52 while Paul was in the city of Corinth on his second missionary journey (Acts 18)
The church in Thessalonica was started shortly before Paul wrote these letters. After a short ministry in the city, Paul was forced to leave town. You can learn the whole story by reading Acts 17 and listening to the backstory to the letters.
Thessalonica was an important port city in the region of Macedonia, and still is today.
Click the links below to listen to the commentary on that section.