Kingdom of Denmark

State · 936–1406 CE · at its largest around 1220 CE

The Danish kingdom consolidated under Gorm the Old and Harald Bluetooth, who adopted Christianity. Under Cnut it ruled an empire around the North Sea.

On its lands while it lasted

Copenhagen (c. 965 CE): Capital of Kingdom of Denmark (965–1406), Kalmar Union (1443–1523), Denmark-Norway (1536–1814).
Jelling stones (c. 965 CE): Runestones raised by Gorm the Old and his son Harald Bluetooth; the larger proclaims Harald's conversion of the Danes to Christianity.
Stockholm (c. 980 CE): Capital of Kingdom of Sweden (980–today), Kalmar Union (1436–1523), Swedish Empire (1612–1721), and 1 more.
Gdańsk (997 CE): Capital of Free City of Danzig (1920–1939).
Minsk (c. 1111 CE): Capital of Principality of Minsk (1111–1313), Republic of Belarus (1992–today).
Riga (1201 CE): Capital of Republic of Latvia (1920–today).
Vilnius (1201 CE): Capital of Grand Duchy of Lithuania (1323–1449), Polish-Lithuanian Commonwealth (1572–1596), Republic of Lithuania (1990–today).
Jelgava (1226 CE): Capital of Duchy of Courland (1734–1793).
Klaipeda (1252 CE): Capital of Kingdom of Prussia (1707–1708).
Kaliningrad (1255 CE): Capital of Duchy of Prussia (1526–1618).
Trakai (c. 1321 CE): Capital of Grand Duchy of Lithuania (1321–1323).
Hanseatic League (1356 CE): Confederation of merchant guilds and market towns that dominated Baltic and North Sea trade; its first general diet met in Lübeck in 1356.
Hanseatic trade route (1356–1669 CE): The Hanseatic League of north German merchant towns, led by Lübeck, dominated Baltic and North Sea trade from London and Bruges to Novgorod, exchanging furs, wax, grain, fish and timber for cloth and salt.
Kalmar Union (1397 CE): Union of the crowns of Denmark, Norway and Sweden under a single monarch, created under Margaret I and lasting until 1523.
Roskilde (c. 1402 CE): Capital of Kalmar Union (1402–1443).