Rhovanion is a huge area in Middle-earth, between the Misty Mountains and the River Running. In the Common Tongue it is called Wilderland. It is the largest of the regions of Middle-earth, and is inhabited by many creatures, both good and evil.
The forest of Mirkwood was once a great forest of good called Greenwood the Great, but in the Third Age Sauron built a fortress called Dol Guldur there, and the forest became inhabited mainly by evil creatures, and thus received the name Mirkwood. The black squirrels, orcs, and giant spiders that dwelt in Mirkwood were all brought forth by Sauron. The Green Elves of the forest remained as the last piece of good in this dreary wood. A road ran through the forest, called the Old Forest Road, but by the Third Age it was in ill condition. It is rumored that anyone who strayed from this path into the forest would be lost forever. After the War of the Ring Mirkwood was restored to its original glorious state.
Mountains of Mirkwood:
The Mountains of Mirkwood are a small yet significant range. They are located in northern Mirkwood, and the Enchanted River, that puts all who touch it to sleep, finds its source here.
Esgaroth and the Long Lake:
The long lake is an oval shaped lake just to the east of Mirkwood that is fed by the River Running and the River of the Forest Mirkwood. The River Running departed from the Long Lake at a waterfall at the southern end of the lake.
Esgaroth is a city of men that was built upon the Long Lake. When Erebor belonged to dwarves, the lake men supplied them with food and water. Esgaroth sent food to the Wood Elves of Mirkwood by river, and was thus a grand economic city. The original wooden Esgaroth was destroyed when the Great Worm Smaug attacked from Erebor, but after the slaying of Smaug by Bard it was rebuilt with gold from Smaug's own hoard.
Erebor or the Lonely Mountain:
Erebor is a mountain just west of Mirkwood and slightly east of the Iron Hills. Erebor was originally settled and run by the Dwarf Thráin I upon his flight from Moria. His kingdom was known as the Kingdom Under the Mountain, and all its rulers were called King Under the Mountain. This became the grandest of the Dwarf-kingdoms until 2770 of the Third Age, when it was destroyed and plundered by Smaug, the Great Worm. The dwarves reclaimed it in 2941 of the Third Age, when the Company of Erebor reached the mountain, and forced Smaug out. Smaug then flew down to Esgaroth, where he was slain by Bard with his Black Arrow.
The Iron Hills are a low mountain range east of Erebor that were inhabited by Grór's folk, Durin's descendants, after 2590 of the Third Age. The Dwarves of The Loney Mountains aided the allied forces of Humans, Dwarves, and Elves in the Battle of Five Armies. Dáin of the Iron Hills became the king of Erebor after the Battle of Five Armies, and the Iron Hills passed out of recorded history forever.
Ered Mithrin or the Grey Mountains:
Ered Mithrin, or the Grey Mountains, is a mountain range north of Mirkwood. Long ago Durin's folk tried to live here, but dragons came and took the chain. The primary dwelling of the dragons is in this range, and it is called the Whithered Heath.
The Gladden Fields:
The Gladden Fields are a marshy area where the River Anduin and the River Gladden meet. This is the place where Isildur lost the One Ring, and where it was later found by Deagol. The Stoors, a hobbit family, lived here.
Azanulibizar or Dimrill Dale:
The Dimrill Dale is the valley outside the Western Gates of Moria. This area is in between two small arms of the Misty Mountains. The Last Great Battle of the War of Dwarves and Orcs was fought here.
The River Silverlode:
The River Silverlode is a great and fair river that flows from the Dimrill Dale and southwards through Lórien. It is one of the grandest tributaries of the River Anduin.
Lórien or Lothlórien:
Lothlórien, originally called Laurelindórinan, means the Golden Wood in the Common Tongue. Lórien was the fairest of all the cities of the Elves. It was west of the river Anduin, and its woods began just where the rivers Silverlode and Nimrodel joined. In the Golden Wood life was preserved by the power of the Lady Galadriel (or Galadhriel) as it had been for thousands of years. This land was protected from the evil and the malice of Sauron.
Lórien was created at some point in the Second Age, based upon the once great city of Doriath. It was founded by Galadriel, the Lady of the Golden Wood. There she dwelt with her husband, Celeborn, and they were the rulers of the city. The Elves of Lórien were called the Galadrim, meaning tree people, for all the residents of Lórien dwelt in the boughs of Mallorn trees; trees with silver bark and golden blossums. The Elves of Lórien, altough of Silvan origin, spoke the language of Sindarin. Early in the Second and Third Ages Elves of Lórien would assist the Elves of Rivendell, but for the most part the Lórien Elves took no part in the world outside the Golden Wood.
The Forest Fangorn:
Fangorn is a large forest near Rohan, and the southern tip of the Misty Mountains. It is one of the oldest forests in the world. It's trees are watered by the rivers Entwash and Limlight. Fangorn Forest once covered all of Eriador and some of the more eastern lands, but was for the most part cut down by men as they moved around Middle-earth. The Old Forest is believed to have been part of the Fangorn Forest. The Ents lived in Fangorn, and this alone shows the age of the forest, for the Ents were the eldest of the living races in the Third Age.
The Forest Fangorn was named after the Ent, Fangorn (Treebeard), the "chief" of the Forest. Alternate names for the forest include the name given to it by the Rohirrim, Entwood, and the many names given to it by Treebeard, including Ambarona and Tauremornalómë.
Rhûn or the Eastlands:
Rhûn is actually not a part of Gondor, but its own region, but little is recorded of it, and so for convenience's sake I have included it here. Rhûn was a large region in the east of Middle-earth where the Easterlings, crude men and servants of Sauron, lived. Little is known of what was here save the Sea of Rhûn, a rather large inland sea, and the large forest to the northeast of this sea.
Rauros, Emyn Muil, and the Dead Marshes:
Rauros is a great waterfall on the Anduin River. It is in close proximity to the
island of Tol Brandir, and the slopes of Amon Llaw and Amon Hen. The Emyn Muil is a rocky, hilly region
nearby the falls of Rauros. The Dead Marshes is a stretch of marshes just southeast of the Emyn Muil, in which
one was once able to see dead faces.