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.
Generally, the highest chance of pregnancy is when sex happens1-2 days before ovulation. If you have a regular 28-day cycle, count back 14 days from when you expect your next period to start. Plan on having sex every other day around that time -- say, days 12 and 14.