From the beginning, God reached out to mankind, and had expectations for them. Here in the first two chapters of Genesis, we find God giving Adam six instructions--see Genesis 1:27-29, Genesis 2:15-17, Genesis 2:24.Only one of these is a prohibition, the one described as a "command"--the one that was eventually broken. There must have been more instructions given to them than what we have specified; Cain and Abel brought sacrifices according to a known practice; and the judgment on the contemporaries of Noah implies known standards of behavior.
This relationship between God and mankind that we see developing throughout Scripture is first described as a "covenant" in the story of Noah: "Behold, I, even I am bringing the flood of water upon the earth… But I will establish My covenant with you; and you shall enter the ark—you and your sons and your wife, and your sons’ wives with you." (Gen 6:17-18) After the flood, this covenant is made more specific: And God blessed Noah and his sons and said to them, “Be fruitful and multiply, and fill the earth. …Every moving thing that is alive shall be food for you; I give all to you, as I gave the green plant. Only you shall not eat flesh with its life, that is, its blood…And from each human being I will demand an accounting for the life of another human being. (Genesis 9:1-5) Any good treaty has requirements for both parties, and this is God’ s side “I establish My covenant with you; and all flesh shall never again be cut off by the water of the flood, ” God said, “This is the sign of the covenant which I am making between Me and you and every living creature that is with you, for all successive generations; I set My bow in the cloud, and it shall be for a sign of a covenant between Me and the earth. (Genesis 9:11-13)
By the time of Jesus, the Law of Moses had become 613 laws that were binding upon Jews, but Jewish tradition had also codified the covenant with Noah as the commandments that all people on earth were obligated to obey. They are given as seven by rabbinical scholars of the third century AD: The prohibitions against idolatry, murder, theft, sexual immorality, blasphemy, eating the flesh of a living animal, and the requirement of maintaining courts to provide legal recourse.
We see the question of the relationship of Gentiles to the Jewish Law surfacing in the early church, as more and more Gentiles were becoming part of the Christian community. There were those who were demanding that all believers conform to the full Mosaic law. At the Jerusalem Council in Acts 15, probably 50AD, James' decision was that Gentiles should obey four basic rules: "Therefore it is my judgment that we do not trouble those who are turning to God from among the Gentiles, but that we write to them that they abstain from things contaminated by idols and from fornication and from what is strangled and from blood." (Acts 15:19-20) This appears to be similar to the idea that the Noah Covenant is binding upon all descendants of Noah-- which is everybody. This is another reminder that people have not changed over millennia—and neither has God.