The Antonine plague also known as Plague of Galen swept through ancient Rome and the Mediterranean from 165 to 180 AD. It first appeared during the siege of Seleucia, a major city along river Tigris. It is therefore widely believed that it originated from China and was likely brought in by Roman troops returning from wars in the near east and trading ships moving westwards.
As the Greek physician Galen described it, the disease caused its causalities to suffer high fever, swollen throat, chronic thirst, cough, vomiting, and diarrhea. There were also instances of red and black rash on the skin.
The strange disease would strike again in the period of 251 to 266 AD. These two separate outbreaks with a mortality rate of 25% almost brought the Roman Empire to its knees. By the end of the scourge, it had claimed about 5 million lives.