Africans were also used in large numbers for slavery because they were easier to buy. During the beginning of the Atlantic Slave Trade, Africans were willing to sell other Africans as slaves to Europeans because they had their own system of slavery.
You could have sex towards the end of your bleeding and then actually conceive 4 or 5 days later with your early ovulation. The probabilities of getting pregnant while on your period are low, but the possibilities are there. This is not the time to have sex if you are trying to get pregnant.
You can't become pregnant if you have sex on your period. That's somewhat true if you have regular monthly periods. However, some women who have irregular periods might be spotting and not actually menstruating, and if that's the case, it's definitely possible you could still get pregnant during that time.