A.D. Science writer David Keys believes that the cause was a natural phenomenon of cataclysmic proportions. The subsequent environmental calamity, he believes, affected human civilization from Mongolia to Constantinople, precipitating plague, famine, death, great migration, the fall of the great Mexican city of Teotihuacan, the Anglo-Saxon victory over the Celts, and may even have played a role in the rise of Islam. We marvel to see no shadows of our bodies at noon, to feel the mighty vigour of the sun's heat wasted into feebleness, and the phenomena which accompany an eclipse prolonged through almost a whole year. The drinking water was so polluted at that time, wine and beer were consumed in large quantities. In fact, lead pipes were used to supply the basement vats to the upper dinning chambers in most great houses of Europe.
Wine is acidic and leached the lead out, and into the bodies of the ruling class.
They went crazy. Lead oxide was also a popular form of face powder up until Victorian times. 543 AD - There was an extraordinary universal plague through the world, which swept away the noblest third part of the human race. Clearly, something dramatic had happened. After Ashoka's death in 232 BC, the Mauryan Empire started to decline and the country was invaded by different tribes until the 4th century when Gupta Empire was established.