Watchful Peace

The Watchful Peace (2540-2941) was a 400-year long period of relative peace in Middle Earth, following the banishment of the Nazgûl from Minas Morgul in 2975 and their subsequent entombment in the High Fells after the fall of Angmar in 2540. Gondor's Wars with the Wainriders (which were conspired in part by the Ringwraiths) also ended shortly before the peace was declared.
While the Ringwraiths didn't return to harass the Free People until their liberation (by their overlord Sauron) in 2940, small conflicts between the different races of Middle Earth continued intermittently, including the Sack of Erebor by the Dragon Smaug (2770), the Battle of Moria (2799) between the Dwarves and Orcs, and a coordinated Corsair raid on Gondor and Dunlending invasion of Rohan in 2758.
The Watchful Peace ended with the return of the Ringwraiths under Sauron and their involvement in the Battle of Dol Guldur, while beginning to usher The War of the Ring.