Acts 16 describes Paul, Silas, and Timothy traveling through Asia Minor during the second missionary journey.
After being prevented by the Holy Spirit from preaching in the province of Asia, they approached Mysia and attempted to enter Bithynia, but the Spirit of Jesus did not permit them.
They therefore passed by Mysia and descended to Troas. There Paul saw a vision during the night of a Macedonian man appealing to him to cross over and help them.
The journey through Mysia therefore forms part of the narrative transition that carried Paul's mission from Asia Minor into Macedonia.