The below is part of my modern history, which honestly I've done the most on.
The Supranational Unions of the world;
African Union:
The African Union started out with the goal of uniting the entirety of Africa in a communal organization in the 1960's, however the early leaders
were fierce independentists and ideologues to varying degree, resulting in the organization starting out small.
The AU has changed over the years, moderating many of its ideological positions and has now essentially become the Northern African Union in
everything but name.
The AU, while not having the degree of integration found in some of the other supranational polities is integrated to a fair degree with a common
currency and single economy and the development of a common political system.
The AU, if considered a single entity would be a Great Power, having the 8th largest economy, and a good sized military.
Asian Common Union:
The Asian Common Union (general english translation) has its roots in the East Asian Defence Union.
In the 1950's, when the CUSR-allied Mongolian government was forced from power in a popular revolution China and Japan were quick to support
them, leading to the formation of the East Asian Defence Union.
This marked the beginning of closer relations between Japan, China, Mongolia and Manjuku.
The ACU is a unique case among supranational entities, while it has a single economy & currency, a common foreign policy and joint military
overall integration has been slow until recently.
The ACU is one of the most powerful polities, having the largest common economy, the largest combined population and among the largest
combined military forces in the world and as a result a significant amount of power in international politics.
East African Federation:
The East African Union came into existance in the 1970's when the nations of East Africa, surrounded on two sides by major blocs came
together to form the East African Community.
Over time the EAC evolved into the EAF.
Despite some cultural and linguistic issues (German, English and Swahili are all official languages) the EAF has integrated more and more over
time and has more or less become a single nation, though its component states are still technically sovereign entities.
The EAF, do to its strategic political and economic position has managed to develop a robust economy (13th largest) and a considerable amount
of diplomatic influence for its size.
Eurasian Union:
The Eurasian Union traces its roots to the first half of the 20th century when the Ottoman Empire and its allies were developing closer relations.
The EaU developed from the Eurasian Community, which itself developed from the Eurasian Defence Union & Eurasian Economic Community.
The EaU has grown over time to include the Caucuses and parts of Central Asia and is likely to continue to grow over time.
The EaU is highly integrated, second only to the EAF and CAS, and many suspect that by the late 2030's it will have fully Federated.
The EaU is generally considered the most powerful entity on Earth, having the second largest economy, the single most powerful military and
a great degree of prestige and 'soft power'.
European Confederation:
The European Confederation, originally the European Community, came into existance in the 1950's when the European powers, uncomfortable
with the CUSR to the East and the growing (though non-threatening) power of the EEC to the South as well as their own individual power
weakening came together to form the European Community, a military alliance and free trade zone.
Over the decades the European Community evolved into the European Confederation, however unlike the EaU integration has been slow and
held-up for many reasons, ranging from sovereignty issues to trade issues to the ever-present situation of Italy, who may or may not (depending
on who you ask) decide to leave the EC to join the EaU.
The EC has a common economy and currency (though Lithuania and Italy have opt-outs), while politicaly it's adopted a multi-speed approach
with some members being more integrated than others.
The EC is generally considered to be the third most powerful polity, having the fourth largest economy, a (theoretical) combined military force
rivaling the EaU and holds a considerable amount of sway in international politics.
North American Community:
The North American Community came into existance in the 1980's when the United States, Canada and Mexico created the North American Economic
Community.
In the 1990's, following the admission of Central America and the Dominican Republic the NAEC was replaced by the NAC.
The NAC is in the process of developing a common economy and their are talks of a common currency and some have even suggested a North
American Parliament, however the direction of the NAC is still in flux, though with regionalism popular in its constituent countries its future looks bright.
If the NAC were to be considered a single entity it would have the third largest economy, a very strong military force and a fair amount of sway
in political issues, given its general good relations with the rest of the world.
Scandinavian Union:
The Scandinavian Union began as a sui generis Union of Denmark, Sweden and Norway in the 1920's.
In the late 30's Finland was admitted and Estland, having close relations, acceded to the Union in the late 40's
Scandinavia is highly integrated, having a single economy and currency, a single military and foreign policy and a high degree ofpolitical integration.
The only thing preventing full federation is the disagreement on what form of government the federated Union should have, that of a Monarchy or
a Republic.
Scandinavia has the 11th largest economy, a moderate sized, but advanced military and a good deal of respect on the international stage.
South African Community:
The South African Community was founded in the early 80's as South Africa and Mozambique became 'newly industrialized countries' and the idea
of regional cooperation and integration began to form.
The SAC has a common economy, however while their is no common currency yet their is a single currency standard and all member nations accept
each others currencies as legal tender.
The Southern African Defence Council, founded in 2002 is responsible for military coordination and integration among the SAC.
South American Confederation:
The South American Confederation (CAS) traces its rots to the 1962 Bogota Declaration, however the South American Union did not come into
being until 1970.
In 1990, following the Treaty of La Plata the SAU became the South American Confederation.
The CAS is highly integrated with a single economy & currency, common military & foreign policy and a high degree of political integration.
While it's possible for the CAS to fully federate at the present time it has not done so as a means of encouraging the remaining South American
nations to join.
The CAS has the 5th largest economy, a respectable military force and good relations with most of the world.
South Asian Union:
The South Asian Union was founded in the 70's as a counterweight to the influence of East Asia and the EaU to the West.
The SAU has'nt changed very much since its founding, only adopting new treaties and integrating.
The SAU has a common currency and economy, a joint military and comm foreign policy, however integration overall, while not being fast,
has progressed at a steady rate and continues to do so.
The SAU has the 6th largest economy, a moderate sized military and a moderate degree of sway in international politics.
Union of South-East Asian Nations:
The Union of South-East Asian Nations was formed in the early 90's as Indonesia, Malaya and Cambodia formed the Association of South-East Asia.
East Timor joined in 1996 and Thailand (though with reservations) in 2000.
The SEAS was transformed into the USEAN in 2001 following the Jakarta Treaty.
The USEAN is in the progress of economic integration, having established a Free Trade Zone and Customs Union.
Overall the USEAN is not very integrated for a variety of reasons, particularly Thailand's (who wants to join the EaU) reluctance.
If the USEAN was a single entity it would have the 14th largest economy.