7 And who then is this, and what is the sign of Him that rises? In the words of the Prophet that follow in the same context, He says plainly, For then will I turn to the peoples a language: since, after the Resurrection, when the Holy Ghost was sent forth the gift of tongues was granted, that they might serve the Lord under one yoke. And what other token is set forth in the same Prophet, that they should serve the Lord under one yoke? From beyond the rivers of Ethiopia they shall bring me offerings. You know what is written in the Acts, when the Ethiopian eunuch came from beyond the rivers of Ethiopia. When therefore the Scriptures tell both the time and the peculiarity of the place, when they tell also the signs which followed the Resurrection, have thou henceforward a firm faith in the Resurrection, and let no one stir you from confessing Christ risen from the dead.
Source: Catechetical Lectures (New Advent)