The Prosperity League was a multinational alliance existing from the Coalition Period to Unification Period, which formed in opposition to the South Sea Coalition. Its constituent states included Montrose, HUM, Rhett, Bagelonia, The Guardian State, and Lucas. Its purpose was to coordinate defensive wartime readiness strategies between the allied states in case of a declaration of war by the South Sea Coalition, to which end the wealthier states such as Montrose and HUM invested in equipment and infrastructure in the other member states to improve their ability to counter a South Sea Coalition attack.
Founding and Coalition Period
The Prosperity League was founded on September 24th, 2018, in response to FlyingGMM being killed by RHIN0SAURUS. Hostilities had been building up for days, and the event sparked the creation of such a coalition. For their part, The Water Boys and Dark Forest Investment Co. created the South Sea Coalition. The rivalry between both of these alliances characterized the Coalition Period.
Decline and Dissolution
Upon the end of the South Sea Coalition (and Coalition Period), the Prosperity League still existed, even though it had no opponents. As new states were formed due to the influx of people in the Repopulation Period, they found friction against the alliances in the Prosperity League, particularly Goomlandia with Bagelonia.
HUM left the Prosperity League in the early Repopulation Period, The Prosperity League remained nominally in existence until the formation of the Sylvian Union, which required its constituent states to have no independent alliances. As such, the alliances from the Prosperity League were broken. However, the only state formerly in the Prosperity League that did not join the Sylvian Union was Bagelonia, which had an alliance with it while the two states existed.
The historian FlyingGMM would make the analysis that while the Prosperity League is no longer in existence, it provided the antecedent to cooperations between former constituent states, including the idea of "western identity" and even the formation of the Sylvian Union itself. Had it never existed, the modern state of western cooperation and cohesion may not be the case.