Anórien - the ‘Sun Land’ - was the region of Gondor directly controlled by Minas Tirith. It was bounded by the Mouths of the Entwash to the north, the River Anduin to the east, the White Mountains to the south and the Mering Stream to the West.

Anórien was one of the two main provinces of Gondor and was named for both Anor (the Sun) and Anárion, son of Elendil. Its chief city was Minas Anor, later renamed Minas Tirith, and it was first ruled by Anárion.

The area of Anórien nearest Minas Tirith was known as the Pelennor Fields. This area contained fertile farmtowns, and long after Ithilien fell to the forces of Sauron, Pelennor Fields was protected from invasion by the long high wall known as Rammas Echor. It was this wall that was being torn down by the orcs attacked by the riders of Rohan as they joined the Battle of the Pelennor Fields.

Beyond the Mering Stream to the west lay the Eastfold of Rohan. To facilitate the calling for aid from Rohan in time of war, beacons were constucted on seven hills that lay in a line between Minas Tirith and the Mering Stream. The first of these beacons, Amon Dîn had served as a fortification and watchpost since shortly after the founding of Gondor. From its summit the fortifications of Cair Andros and foes crossing the Anduin at Cair Andros could be seen. From east to west the other six beacon hills were named Eilenach, Nardol, Erelas, Min-Rimmon, Calenhad and Halifirien. These beacons were always manned and kept supplied with fresh horses for riders summoning aid and with ample fuel for beacon fires. When Gandalf and Pippin entered Anórien after leaving Rohan they saw some of the beacons being lit and passed three riders heading for Rohan to summon aid.
Encyclopedia entry originally written by Ringhilwen