In the Bible, it can refer to either:
Dedan in the latter meaning is first mentioned in the Book of Ezekiel, (Chapters 27 and 38). Chapter 27 is a roster of the trading partners of the city of Tyre (today in modern Lebanon), where Dedan is noted as a nation or kingdom which traded in saddle blankets (Ezekiel 27:20).
The oasis kingdom is also mentioned in the the prophetic vision of the war of Gog and Magog (Ezekiel 38; see also, Revelation 20:8), and appears to be a nation of significance in this end-times prophecy of Ezekiel.
In Ezekiel 38:13, Dedan is joined with Sheba, and "Tarshish and all her strong lions", all these nations joining together to inquire of the advancing armies of Gog: "Have you come to plunder? Have you gathered your hordes to loot, to carry off silver and gold, to take away livestock and goods and to seize much plunder?"