When Daniel prayed this, Judah had been scattered for about 70 years, and they were just about ready to go back to the Promised Land. God was just about ready to release them. Daniel was concerned due to what he saw in Babylon; it discomforted him. He likely saw some of the same conditions existing in Babylon that had caused the Jews to go into captivity in the first place almost 70 years before. His fears were justified because, when Ezra and Nehemiah went back to rebuild the Temple and then the wall around Jerusalem, very few Jews went back. In fact, it was such a small number by Ezra's count that he called a fast about it. He wanted to make sure that the people would be hidden on the way so that nobody would see them making the trip back to Judea and consider them "easy pickings."
When the church was finally begun in AD 31, Peter went to preach in Babylon because there was still such a large colony of Jews there. Indeed, they stayed in the world—in Babylon—and continued to multiply.
We can read between the lines of Daniel's prayer and understand that he was anxious over their return. Quite a number of commentaries say that they feel that this cannot be all that Daniel prayed. Really, all that we have here is an outline of what he said, the high points. After praying it, Daniel went back to his office or to his home and jotted these things down so that they would be remembered. God undoubtedly inspired that. So we are actually seeing only the essence of what he said. He certainly went into a great deal more detail with God.
When we pray for repentance, we go into detail about things that we personally know about—especially those things that happen in our lives and perhaps those things that happen within God's work, of which we were aware. We do nothing about them then, but we certainly can ask God to forgive them.
Daniel begins by establishing between him and God that he, Daniel, understood that God is faithful. He keeps His covenant. He stands by Leviticus 26 and Deuteronomy 28. When something goes out of God's mouth, it does not come back to Him empty (Isaiah 55:11). There are no "hollow threats" with God! Do we understand that? His faithfulness is one of the things that makes Him God. He can always be depended upon. He is Jesus Christ—the same yesterday, today, and forever (Hebrews 13:8). "For I am the Lord, I do not change" (Malachi 3:6).