The Christians are responsible for the Desertification of a major Northern portion of the Sahara region...during Roman Times, a vast amount of this area was still covered with plant & animal life. But the Romans needed to capture large quantities of predator animals to use in the circuses held in the Coliseum at Rome, to  "eat" Christians. In order to do this, they would set large swaths of the Sahara grasslands on fire to aid in the capture of required animals. The burned-over grassland never recovered & caused the direct increase of vast areas of  "Desertification of the Sahara...