Exodus 19:2

To the desert of Sinai, i.e. to that part of the desert which adjoined to Mount Sinai, as Rephidim, from whence they came, was in that part of the wilderness adjoining to Horeb, which was another part of the same mountain. See Exodus 17:6. So they seem to have fetched a large compass, and to have come from one side of the mountain to the other.