For 2500 years “death reigned from Adam to Moses” (Rom. 5:14).
During this period of history it was demonstrated that “death passed upon all men,” not because the Law of Moses had condemned them to death, but simply because they were the offspring of fallen Adam, and depraved by nature. Entirely apart from the Law, “sin, when it is finished, bringeth forth death” (Jas. 1:15). Thus “death reigned from Adam to Moses, even over them that had NOT sinned after the similitude of Adam’s transgression.”
For 1500 years, under the law, “sin… reigned unto death” (Rom. 5:20,21).
Sin had surely risen to its height during Paul’s early years. Christ had been crucified and even after His resurrection His enemies had stood by that awful deed. Israel had joined the Gentiles in declaring war on God and His anointed Son (Psa. 2:1-3) and Saul of Tarsus was the leader of the revolt. It was no longer merely a matter of sin; it was now rebellion.
For 2000 years, “grace [has] reigned, through righteousness, unto eternal life, by Jesus Christ our Lord” (Rom. 5:21).
Thus we are now living under the reign of grace. As “DEATH REIGNED from Adam to Moses” (Rom. 5:14); as SIN REIGNED “unto death” after “the Law entered”, so now grace abounds, THAT GRACE MIGHT REIGN “through righteousness unto eternal life by Jesus Christ our Lord” (Rom. 5:20,21).
For 1000 years the Lord Jesus Christ will reign upon this earth (Rev. 20:1-6), as King over Israel and the nations.
The kingdom will then be delivered over to the Father (I Cor. 15:24-28).
For all eternity the Father, Son and Holy Spirit will reign in the person of Christ (Rom. 11:36; Eph. 1:10).
Note: From Adam to the present day God has always been “on the throne”, but rather than ruling directly, has overruled in the affairs of men. source