Do we also know where the plague came from before that? I mean, it can't just pop up out of nowhere, right? With ebola, for example, the virus had been known for quite a while, but it had only appeared deep in the jungles etc, with the biggest causalities to a single outbreak being a native village sometime in the 70s, before the outbreak a few years ago.
Pinpointing to a specific village or so will be very difficult because there is so little documentation.
So you move over from classic history methods to the realm of DNA investigations.
When I dig in:
There is already a claim that of the dozen or so known different DNA strains of the plague bacterium a new one mutated around 700 years ago (the calculation points at 728 year).
DNA mutation chronology is a powerful tool, but ofc with an inaccuracy, but that 728 does fit nicely the plague we talk about.
And back to classic history:
There is ofc the Justinian plague pandemic of 541, that came to Byzantium from Africa. And that was another strain of the same plague bacterium.
That points to a much older mother source of the plague.
The DNA research comes from her current DNA mutation data to a date of more than 2,000 years ago for the mother source.
So the question is not only
where did it start, but considering that the bacterium has been around for ages, in a kind of dormant state,
why did it break out ?
With the Black Death it could have been the mutation of the new strain being more lethal. IDK
With the Justinian plague there are theories that it was caused by the extreme bad life conditions in the two years 535-536 where the earth climate cooled down and the amount of sun decreased more than ever in known recorded history.
=> famine from crops not growng, etc, etc.
Theories are a very big volcano eruption, clouding the sun, in Indonesia (same spot as the Krakatau).
There is still lots to find out
EDIT
To my surprise, continuing to dig in the relation between the original Turkish cow culture being less affected than the Mongolian horse cultures (horses need good grass), I see there is an old thread from 2005 on CIVfanatics about this volcano eruption !
Interesting reading
https://forums.civfanatics.com/threads/a-guide-to-535ad-catastrophe-theory.116880/
