The Scandinavian Union refers to a historical alliance that existed between the kingdoms of Denmark, Norway, and Sweden from 1397 to 1523. This union was established under the rule of Queen Margrethe I and aimed to strengthen the three kingdoms against external threats and to promote trade and cooperation among them. The union faced various challenges, including internal conflicts and power struggles, particularly between Sweden and the other two kingdoms. Ultimately, the union dissolved in the early 16th century, leading to the emergence of independent states, although the countries continued to share cultural and historical ties.