Dispersions of Israel
Colonies
Isaiah 49:19 For thy waste and thy desolate places, and the land of thy destruction, shall even now be too narrow by reason of the inhabitants, and they that swallowed thee up shall be far away. 20 The children which thou shalt have, after thou hast lost the other, shall say again in thine ears, The place is too strait for me: give place to me that I may dwell.
This is talking about the nations which eventually descended from the children of Israel, that they would keep spreading out into the world. It describes the Saxon peoples of the past 2500 years through the colonial period.
Reconciliation
The purpose of Christ's ministry is recorded in Luke chapter 4, where He Himself quotes from the later chapters of Isaiah:
Luke 4: “16 And he came to Nazareth, where he had been brought up: and, as his custom was, he went into the synagogue on the sabbath day, and stood up for to read. 17 And there was delivered unto him the book of the prophet Esaias. And when he had opened the book, he found the place where it was written, 18 The Spirit of the Lord is upon me, because he hath anointed me to preach the gospel to the poor; he hath sent me to heal the brokenhearted, to preach deliverance to the captives [the Israelites, who were described as prisoners and captives by Isaiah], and recovering of sight to the blind [we should know that we are Israel!], to set at liberty them that are bruised, 19 To preach the acceptable year of the Lord. 20 And he closed the book, and he gave it again to the minister, and sat down. And the eyes of all them that were in the synagogue were fastened on him. 21 And he began to say unto them, This day is this scripture fulfilled in your ears.”
Note that He stopped before proclaiming the Day of Vengeance, which has to do only with His second advent, and not His first.