After they were filled with the Holy Spirit, they “began to speak with other tongues, as the Spirit gave them utterance.” These “other tongues” are not unknown tongues. There were many tongues spoken by Jews throughout the Roman Empire.
Holy Spirit, Tongues, Works Of God, Tongue Is A Fire, Devout Men
Those who were scattered preached the Gospel everywhere they went. Hundreds of individual evangelists were giving the Gospel to thousands of souls, and the message became known over the whole area.
Persecution, Devout Men, Great Persecution, People Scattered