Acts 13:20

And after that he gave unto them judges about the space of four hundred and fifty years, until Samuel the prophet.

This statement belongs to Paul's Sabbath sermon in the synagogue at Antioch in Pisidia. It was spoken on the Sabbath after the reading of the law and the prophets, when the rulers of the synagogue sent an invitation for a word of exhortation, and Paul stood up and beckoned with his hand, calling for attention with Men of Israel and ye that fear God give audience. In that address he rehearsed how the Lord had dealt with the Jews from their deliverance from Egypt and Egyptian bondage, carrying the review through the time of the judges.

That rehearsal of divine dealings was made to lead to the promise of a Saviour of the seed and line of David, descended from David. Paul then preached Jesus as that Saviour of men, identifying Him as the promised Saviour and the Messiah of prophecy foretold in prophecy. Thus the history from Egypt onward becomes the setting for his announcement of Jesus as the promised Saviour from David's line.