To define literally, pandemic is an outbreak of a disease that occurs over a wide geographic area and affects a high portion of population. There is a sharp difference between epidemic and pandemic. Both have the same meanings but epidemic is limited to a certain area or country while a pandemic has vast magnitude and it spreads over countries.
Briefly viewing the history in chronological order, the firstever evidence about epidemics is found about Circa (3000 B.C.) in China. Now these places are called Hamin Mangha and Miaozigon. The nature of this epidemic is unknown.
Plague of Athens outbroke in 430 B.C. causing the death of almost 100,000. Its exact nature is also unknown. It affected Athens (Greek).
Antonine Plague in the form of smallpox engulfed 5 million people of Roman Empire in 165-180 A.D.
Plague of Cyprian killed 5,000 people a day in Rome. Its duration was 250-271 A.D. Its cause is also unknown.
Plague of Justinian (541-542 A.D.) abolished 10% of the world’s population by occurring periodically in the Byzantine Empire. It was a Bubonic Plague (infection in lymphatic system caused by bite of rat flea and transfers from direct contact or cough).
The Black Death 1346-1353 moved from Asia to Europe. It killed 75-200 million people of Eurasia and North Africa. It was also a bubonic plague and considered to be one of the deadliest plagues in the world.
Cocolizitli epidemic spread from 1545 to 1548 in Mexico and Central America.
11th Century Leprosy over shadowed Europe causing deformities in masses. It caused enteric fever and the death toll was 15 million.