What is a full description of the 'Black Death'

The black death was an illness in 1347 to 1351.

It killed 75-200 million people and it was the most devastating pandemics in human history. People thought that they had done something wrong so they started praying to god and hurting themselves to show that they were sorry, hoping that god would notice and forgive them. Although, the Black Death had nothing to do with god. The symptoms of this disease were painful swellings (buboes), these swellings or buboes, would appear in the armpits, legs, neck or groin. A bubo was at first a red colour. The bubo then turned a dark purple or black. People started going crazy running around and shouting for forgiveness, if you survived, you were lucky.