Has there ever arisen a nation-state (building/birth/creation of a new nation state) without violence/war/extreme subordination? But rather peacefully, organically, with all parties and neighbours being enthusiastic?
Iceland would probably count. It left its union with Denmark in 1918 at the end of a peaceful independence movement. However, it continued to share Denmark's king as head of state until 1944, when Nazi occupation of Denmark made that problematic.
The Icelandic independence movement was peaceful from its start in the post-Napoleonic period to the accomplishment of independence in 1944. Common explanations for the peaceful nature of Iceland's independence struggle include:
- Iceland's distance to Copenhagen.
- Iceland's homogenous population.
- The accommodating responses of Denmark to Icelandic demands.
- The unwillingness of Denmark to respond violently, in part due to a respect for Icelandic culture but also an unwillingness to shoulder the costs of quelling the Icelandic independence movement.
- The peaceful trends in the Nordic region after the Napoleonic Wars.
I'd include the partition of Czechoslovakia into the Czech Republic and Slovakia. According to Wikipedia,
The separation occurred without violence, and was thus said to be "velvet", much like the "Velvet Revolution" that preceded it, which was accomplished through massive peaceful demonstrations and actions. In contrast, other post-communist break-ups (such as the Soviet Union and Yugoslavia) involved violent conflict. Czechoslovakia is the only former Eastern bloc state to have an entirely peaceful breakup.