One of the earliest plagues for which we have multiple contemporary sources is The Plague of Justinian.
Justinian was the Eastern Emperor, or Byzantine Emperor, in Constantinople from 527-565. A long reign which promised much but in the end delivered very little. Justinian's big policy was the recovery of the Western Roman Empire (renovatio imperii), and although he made numerous gains, in the end it was a failure. Rome was never to rise from the ashes. In fact, as a portend of things far in the future for Byzantium, a greater threat arose from the East in the form of the Persian Empire.
Yet for lawyers of my generation, it was Justinian's Civil Code that marks his reign as one of great importance to the history of Europe. Even today the Code remains the core of many European civil law codes. Justinian spoke Latin, probably the last Emperor to do so as a first language, and his code is written likewise in Latin - Corpus Juris Civilis. I bear the scars to this day of a summer term spent in the long ago 1960s trying to cope with both the Latin and the law.
However, the event of his reign which had the most impact at the time was The Plague (Bubonic) of 541-542. It is thought five thousand died in Constantinople alone, where even the Emperor himself succumbed. Justinian was, however, one of the fortunate ones who survived an attack. As the cause of the plague was put down to God's anger at the sins of
the people so the Emperor's recovery was also ascribed to God's intervention
It has been argued that it was the plague which really brought Justinian's plans for the recapture of the western part of the empire to a halt. There simply was not enough money left in The Treasury as the tax take fell, in the wake of businesses and farming collapsing (shades of 2020). Grain prices went through the roof also because of the collapse of agriculture, hitting the poor disproportionately (again, perhaps, shades of 2020).
Although the plague died out in Constantinople in 542, it continued to spread across much of Europe, even reaching England in 664, as attested to by Bede. The Saxon word to describe the plague was on-flyge, or on flying, referring to the rapidity of its spread. No social distancing in the seventh century. In fact no understanding of the cause of the plague, or answers as to remedies.
The leading doctor of The Ancient World , whose influence was felt for centuries right up to the modern era of medicine, was the Greek, Galen. Galen, of course, did not understand either the causes of plague nor therefore the remedies (he had lived, some centuries before The Plague of Justinian, in Rome). His only advice being, 'Leave quickly, go far away, and return slowly'. The last piece of his advice is as relevant today as it was then, as our own Government struggles with the question of how and when to end lockdown.