John did not limit his message or ministry to one place or one group of people. Luke makes it clear that John went from place to place. Sounds to me like John moved up and down the Jordan River and reached out to people on both sides of the river. John may have had the opportunity to call Jews, Gentiles and Samaritans to repentance and faith. We don't know for sure.
John invited be people to be baptized as a sign of their repentance and return to God. The people John baptized were responding to his invitation to repent. We need to listen to John's call to repent and return to God.
Christians are sent by Jesus to reach out to people on both sides of the political fence, to call people regardless of their faith or lack of faith to return to Him. It may not be easy to do. It was not easy for John or for Jesus either. But we still need to do it.