How early was this sacrificial system known?

Answer

"By faith Abel offered unto God a more excellent sacrifice than Cain, by which he obtained witness that he
was righteous, God testifying of his gifts." Heb. 11: 4. See Gen. 4: 3-5; 8: 20.

16. How did Christ reprove those who, though familiar with the letter of the Scriptures, failed to understand them?
What scripture shows that the Roman emperors ruled the world?
22. How many of the commandments is it necessary to break in order to become a transgressor of the law?
What is the strength of sin?
7. What questions asked by its worshippers indicate the great station to which this beast-power was to attain?
When was the papal head of the first beast of Revelation 13 wounded?
What did John see in the right hand of Him who sat on the throne ?

Questions & Answers are from the book Bible Readings for the Home Circle