Accursed Years...

One of the many names given by tradition to the period of Sauron the Great's first dominion over Middle-earth. Other names- the Black Years, the Dark Years- betray equally bitter memories of the latter part of the Second Age, when Numenor grew in power while men and elves of Middle-earth groaned under Sauron's tyranny or fought desperate wars for their very existence.
Sauron established this early dominion by means of the Rings of Power. These were forged in Eregion, not by the Lord of Mordor but by the High-elves of Celebrimbor's House, seduced for this purpose in the days when Sauron's treacheries were not readily apparent. Under his tutelage, the Elven-smiths grew skillful at this craft and succeeded in forging, first lesser Rings with limited powers, then the Nine, the Seven, and the Three.
The One Ring was forged by Sauron himself- and from the moment he first put it on and spoke the Ring-spell, his power in Middle-earth waxed, until many of the Free Peoples were defeated or enslaved. The Accursed Years had numbered nearly two thousand before the Last Alliance of Elves and Men took Sauron's Ring, cast down the Dark Tower and laid his realm in ruin, thus ending the Age.
From The Tolkien Companion by J.E.A. Tyler