The Plague
During the final phases of the Yetian Wars of Reconquest, thousands of Sizzlean soldiers were shipped off to Yetia to fight back against the imperialistic north, which was followed by countless reports of some-kind of deadly flu spreading across Yetia. Despite Sizzlean forces being sent home once this disease was identified it was too late as the disease had quickly spread throughout Yetian society, beginning to exhibit more deadly symptoms such as vomiting and swollen lymph nodes. The disease quickly became rampant in Yetia, with all major cities crippled by the disease as most of the government became sick, with their queen also succumbing to the plague with only one young heir surviving. Hoping to escape from the spread of the disease, refugees from Eurasia quickly began spreading the illness to the Americas and the pacific, which were thought to be largely clear of the disease due to the lack of major nations in the regions at the time.
With no government remaining, Yetia was essentially couped by the nation's health service, transforming it into a technocracy dedicated to the development of a vaccine and cure, leading to the development of several medications that lessened symptoms and experimental vaccines. The first two states to fully begin collapsing were Sarpistan and Sizzlean Abard, with only international forces keeping the peace.
By the end of 64 the Yetian Vaccine was quickly becoming much more effective to the point of being put into public use, with the vaccine being offered to all Yetians for free and also being sold abroad to other countries, with most countries quickly recovering apart from more harder hit locations such as Sizzlean Abard, which had largely fallen into anarchy with little to no authority remaining as Capetown was rendered uninhabitable. By the first of January in 65, The Plague had mostly concluded.