In Acts 1:8, Jesus said to the disciples, “But you will receive power when the Holy Spirit comes on you; and you will be my witnesses in Jerusalem, and in all Judea and Samaria, and to the ends of the earth.” (NIV)
What does “the end of the earth” mean here? Joel Green’s explanation is good, I think.
“The story related in Acts begins in Jerusalem and ends in Rome, with the plan of the book thus giving form to the centrifugal shape of the mission it recounts… Although in the literature of Greco-Roman antiquity the meaning of the phrase ‘the end of the earth’ was used to refer to Spain, Ethiopia and so on, one must inquire into how this phrase functions in this context… Acts 13:47, with its citation of Isaiah 49:6, where the phrase ‘the end of the earth’ is again found but with the sense more transparent: ‘everywhere,’ ‘among all peoples,’ ‘across all boundaries.’ Luke’s evident dependence on the Isaianic eschatological vision elsewhere provides corroborative evidence for the conclusion that the narrative encourages an identification of ‘the end of the earth’ with a mission to all peoples. Jew and Gentile. This underscores the redemptive-historical continuity between this text and tis Isaianic pre-text (also Is 8:9; 45:22; 48:20; 62:11; cf. Deut 28:49; Ps 134:6-7; Jer 10:12; 16:19; 1 Macc 3:9)… Moreover, our identification of ‘the end of the earth’ as a reference to the universal scope and not the geographical goal of the mission suggests that the story of Acts does not end with the close of the narrative in Acts 28:31. Rather, the challenge to mission reaches beyond the narrative to Luke’s subsequent readers.” Joel B Green, “Acts of the Apostles” in Dictionary of the Later New Testament and its Development, edited by Ralph Martin and Peter Davids (Downers Grove: IVP, 1997), 14-15.