jan 1, 3000 BC - Neolithic decline

Description:

The Neolithic decline was a rapid collapse in populations between five and six thousand years ago (approximately 3000 BC) during the Neolithic period in western Eurasia. The specific causes of that broad population decline are still debated.[1] While heavily-populated settlements were regularly created, abandoned, and resettled during the Neolithic, after around 5400 years ago, a great number of those settlements were permanently abandoned.[1] The population decline is associated with worsening agricultural conditions and a decrease in cereal production.[2] Other suggested causes include the emergence of communicable diseases spread from animals living in close quarters with humans.

In October 2010, medical geneticists suggested that all three of the great waves of the plagues originated in China.

https://en.wikipedia.org/wiki/Neolithic_decline
https://en.wikipedia.org/wiki/Black_Death#cite_note-china-29