Djingis Khan and his followers killed 40 million, Alexander the murderer sat Persepolis on fire, Romans built Colosseum for Entertainment by killing,,,, in Iran Khayam and his most accurate calendar,,, Khawrazmi and algorithm,,, Razi and alcohol, sulfric acid,,,Birouni calculating earth's radius and mentioning dry land on west of Europe (North and South America),,, Avicenna ,,,Iran has contributed much to the world,