Clearly, the first-person singular indicates that this is no longer a description about Daniel, but Daniel himself writing about his dream or vision. He had this vision at night, as he saw the 4 winds of heaven stirring up the great sea, the Mediterranean Sea.
Somehow the territory of Gad was in the south. Now we have the southern borders of Israel just as it was described in the preceding chapter. This southern border in Numbers, chapter 34 was also vague. Here the border goes almost to Egypt, to the great sea, or the Mediterranean Sea. Tamar was the start of this southeast border. Meribath-kadesh was in the wilderness of Zin, south of the Dead Sea.