What country did a Muslim named Amar ibn Al as cross into with an army of 4,000 men in 639?​

Hee the american public did not truly take in the horror of adolf hitler's regime until years after the existence of concentration camps was first reported in american newspapers. partly this was the fault of the media, which did not give prominent placement to news of the holocaust. what other factors do you think contributed to the long delay in understanding the holocaust?