Generically, a Galilean is an inhabitant of Galilee. The New Testament notes that the Apostle Peter's accent gave him away as a Galilean (Matthew 26:73 and Mark 14:70). The Galilean dialect referred to in the New Testament was a form of Jewish Palestinian Aramaic spoken by people in Galilee from the late Second Temple period (530 BCE) through the Apostolic Age (c. 100 CE). Later the term was used to refer to the early Christians by Roman emperors Julian and Marcus Aurelius, among others.
After some early expeditions to Galilee to save the Jews there from attack, the Hasmonean rulers conquered Galilee and added it to their kingdom.
The Galilean Jews were conscious of a mutual descent, religion and ethnicity that they shared with the Judeans. However, there were numerous cultural differences.
The Pharisaic scholars of Judaism, centered in Jerusalem and Judea, found the Galileans to be insufficiently concerned about the details of Jewish observance – for example, the rules of Sabbath rest. The Talmud says that Yohanan ben Zakkai, a great Pharisee of the first century, was assigned to a post in Galilee during his training. In eighteen years he was asked only two questions of Jewish law, causing him to lament "O Galilee, O Galilee, in the end you shall be filled with wrongdoers!"