Kalmar Union

Short definition from Wiktionary

Proper noun

1. 1
   A personal union in Scandinavia from 1397 to 1523, agreed at Kalmar in Sweden, joining under a single monarch the three kingdoms of Denmark, Sweden (including much of present-day Finland), and Norway, together with Norway's overseas colonies (then including Iceland, Greenland, the Faroe Islands, and the Northern Isles of Orkney and Shetland).