The Plague of Justinian is possibly responsible for the failure of the Roman Empire to reunite (Justinian had reconquered Italy and if he was able to secure those holdings European history might look more like Chinese history). Later iterations of the plague might have been responsible for the rise of the Muslim empires. https://en.wikipedia.org/wiki/Plague_of_Justinianhttps://pubmed.ncbi.nlm.nih.gov/22992565/
The Plague of Justinian is possibly responsible for the failure of the Roman Empire to reunite (Justinian had reconquered Italy and if he was able to secure those holdings European history might look more like Chinese history). Later iterations of the plague might have been responsible for the rise of the Muslim empires. https://en.wikipedia.org/wiki/Plague_of_Justinian https://pubmed.ncbi.nlm.nih.gov/22992565/