Icelandic Commonwealth

State · 936–1271 CE · at its largest around 936 CE

A self-governing society of chieftains in Iceland without a king, with its assembly the Althing. Icelanders submitted to the Norwegian crown in 1262–64.

On its lands while it lasted

• Thingvellir National Park (c. 936 CE): Capital of Icelandic Commonwealth (936–1262).
• Prose Edda (c. 1220 CE): Old Norse handbook of poetics and mythology written by Snorri Sturluson in Iceland, a key source for Norse mythology.

More on Wikipedia.