European Union (The 21st Century)

The European Union was a continental union consisting of many European states. It started out as the western european union in the 1950s with the treaty of rome then its final form began in 1993. Most of its countries used the euro as its currency. Due to numerous issues, the union collapsed in 2028.

Reasons for its collapse
The EU collapsed for several reasons

Economic Crisis:
the 2008 financial crisis put a few of its nations in financial trouble: Greece, Spain, and Italy. Although none of these countries declared bankruptcy, it was a sign of the EU's economic vulnerability.

Border Control:
With the recent terrorist attacks in France and Belguim, many countries began putting tight restrictions on their borders to keep out syrian refugees.

Brexit:
On June 24 2016, The UK, the EU's 2nd strongest economy, voted to leave the EU via referendum. Later, Scotland held another referendum for independence because they actually wanted to stay in the EU. As a consequence, the british pound was devalued (prices went up in the UK), the UK has greater flexibility in their border control and economy, and the collapse of the EU was further hastened. Iceland which was previously planning to join the EU by 2019, cancelled its bid.

Final Collapse:
The secession of the UK inspired other countries to leave. France left in 2021 due to its increasing unpopularity among french. Greece left a year later, being the country with the least favorable view of the EU. These 3 countries were replaced by Bosnia and Herzegovina in 2019 and Scotland in 2021. Iceland was originally slated to join in 2019 but cancelled their bid as a result of brexit. Serbia cancelled as a result of right winged nationalism, increasing unpopularity of the EU, and relations with Russia. Even Germany, the country holding the whole thing together wasn't safe. They left in 2026, resulting in the final collapse of the European Union and with it, the euro.

Aftermath
European unity was greatly disrupted by the collapse of the EU. Although many of the former EU countries were (and are) part of Nato, it gave Russia more leverage in europe and led to Turkmenistan, Uzbekistan, and Tajikistan joining the Eurasian Union.

Successor
Due to a cooling down in relations between the Eurasian Union and Nato, the 2nd cold war eventually ended with the formation of the Eurasian League. This new union was less decentralized than its predecessor and it gave its members greater flexibility in their borders.