"Peter, an apostle of Jesus Christ, to the strangers scattered throughout Pontus, Galatia, Cappadocia, Asia and Bithynia" (1 Pet. 1:1).
These were the ecclesias of Asia Minor which were the scene of Paul's earliest labours.
Peter was the "apostle to the circumcision" - to the Jews.
These brethren and sisters whom he wrote were Paul's first Gentile converts.