Dalmatia was a mountainous region on the eastern shore of the Adriatic Sea, across from Italy. The Dalmatians were an Illyrian (Greek) tribe, or a group of tribes that banded together. They came from the area around the town of Delmion (or Delminium). Their attacks on ships at sea caused the Romans much difficulty until the emperor Octavian (also known as Caesar Augustus) brought them under control in 33 BC.
At the time of the apostle Paul, Dalmatia was the name of the Roman province. Its southern boundary was Macedonia, but its northern boundary is uncertain. The New Testament gives one reference to this province. In 2 Timothy 4:10, Titus is mentioned as having traveled there. We are not told why he went. It may be that Paul had organized some churches there. It is also possible that Titus went there to teach about Christianity in a new area.