Misty Mountains

The real world inspiration for the Misty Mountains was provided by the Swiss Alps. The mountains of Moria were specifically mentioned by Tolkien as being inspired by those he saw travelling the region. Inspiration also came from the Poetic Edda. This is a group of old Norse poems that profoundly influenced the poetry and heroic literature of the region.
Apparently, Morgoth created the Misty Mountains explicitly as a barrier to those hunting his minions. In this sense, a lot of the geography is logical. It also helps explain part of the long running history of evil creatures living here. Literally the only balrog left after Morgoth's fall lived here. Similarly, the only major orc and troll populations outside Mordor are here.
The Misty Mountains, where Moria is located, proves very interesting in a political sense. It has many caves outside Moria that host goblins in large numbers. One of the main elven kingdoms is also located in the Misty Mountains, another traditional enemy of dwarves in Middle Earth. Then there are the eagles that live in this area. The actions of the dwarves appear to provoke involvement in the area by goblins, orcs and the balrog – all of which threaten not just the dwarves in Moria but also the eagles and elves. This history of inviting known enemies and the reputation of inviting dragon attacks (like the Lonely Mountain) would probably go a long way in making relations between the dwarves on one hand and elves and eagles on the other rather frosty.
This geographic proximity to other major political actors will pose as an important factor in our analysis. The Lonely Mountain is a rich source of minerals, but by virtue of its name you can suspect it is much more isolated. Thranduil’s caverns were a solid 50 miles away and Lake Town was around 25 miles. Compare that to Moria, whose east gate is only 17 miles from Lorien.
However, as noted in the section on Moria, I think that Elrond would actually be mush more friendly to Moria than the rest of the elves in the region. I get into why there. For here, let us recognize that Elrond would see the restablishment of Moria and an alliance with it as beneficial to his security. Other elves would likely suffer, but Rivendell could see many of his regional threats eliminated.
The eagles, while they would be seriously annoyed with the seeming reckless behaviors of the dwarves, would likely to prefer their residence to that of orcs and the balrog. If we remember, the eagles would use preeventative war doctrines to deal with threats. They were also literally created to counter Morgoth and Sauron. But the balrog lives underground, not a place the eagles would be able to get to. So, in order for them to eliminate the underground threat of the Moria orcs, trolls and balrog, an alliance with the dwarves would be useful. The dwarves would either outright eliminate the threat or be useful bait to tempt these enemy forces into the open. Once that happens the eagles can kill the balrog themselves. Plus, combined arms tactics are always going to be better that any single branch in isolation. No matter how powerful the eagles are in their own right, an alliance with a group able to provide heavy infantry would be highly beneficial.
Now, the alliance between these forces would place under their control essentially all trade through the Misty Mountains. Trade through the mountains would have few options, high costs and risk. Due to this, it is likely that it would only be profitable to trade across the Misty Mountains if there is a significant volumn that single entities can participate in. This means that small players are likely goingto be shut out. Essentially, this creates a trade based oligopoly with its collusion, lower competition and thus higher prices for consumers. Any decision taken by Moria, Rivendell or Isengard would be influenced by and in turn influence the other powers mentioned here. In real world oligopolies, cooperation leads to the same inflated prices and restriction of supply one would expect in monopolies. This is done in part to inflate profits, but also to stabilize unpredictable markets.
Interesting to me is a real world phenomenon where cartel members cooperate with each other to maximize the size of the market. However, they then compete with each other for a percentage of the market they collectively expand. What happens is firms will not increae their prices, as those with lower prices will generate more business for themselves. This means the other actors will not increase prices to match and thus gain market share at the expense of the firm that did. But lowering prices has the opposite effect. Market share will shift to the firm that does lower prices, thus inducing the other firms to lower theirs as well. This means that price drops will gain a small and short term boost to profits with the cost of starting a price war.
I suspect that this would form the basis of relations between Isengard, Moria and Rivendell. Now, in real world oligopolies, competition can be fierce. Nor does there actually have to be direct communications for there to be collusion. But the relationship between Rivendell and Moria, plus Saruman being on the White Council, suggests to me that there would be more of an explicit cartel. Rivendell's central position, elven values of cooperation and negotiation, plus being the main actor at first with links directly with Moria and Isengard suggest that it would take the leading role. Thus, the Misty Mountains would be the center of a trade based group similar to OPEC. Each member would cooperate in setting prices and quality standards for using trade related infrastructure and services through the Misty Mountains. The goods and services traded would probably be the main source of competition. However, there is enough differences between the produce of the three realms that at first, this cooperation would probaly not be a major factor in the breakdown of relations.
Several important historical events are centered around these mountains. I have already mentioned elsewhere the battles that led to the formation of Rivendell and the unleashing of Durin's Bane. But Gundabad is important as a centerpoint of Mordor's influence as well. This peak was in the middle of Angmar and thus the Witch King's base of operations. When this peak fell, it was never really recovered. Moria was essentially forever cut off from the Iron Hills. During the War of Dwarves and Orcs, the dwarves eraticated all the resident orcs, but failed to occupy the mountain after. The victory thus had no long term geopolitical significance.
Thorin's Company accidentally came across Goblin Town when crossing the High Pass, with huge importance. Here the One Ring was recovered by Bilbo. Then, the Goblin King was killed, causing the mobilization of orcs and wargs and thus provoking the Battle of Five Armies. The rally point for this was Gundabad.

Geography

They get up to 12,000 feet high and run north to south for 795 - 900 miles depending on sources. They are meant to be similar to the Alps. According to the Atlas, alpine glaciation and volcanic activity were responsible for the distinctive features of the range – including geological features mentioned explicitly by Tolkien around Moria. Apparently the mountains were much taller originally, so we can assume erosion has been a noticable phenomenon over the course of the history of the range. Caradhras itself is the tallest mountain in the range at 17,500 feet.
The far north had Gundabad - the site Durin the Deathless awoke at. Also home to many orcs. Also close by was Mount Gram. This too was controlled by the orcs that invaded the Shire. The gap between this mountain and the Grey Mountains is the northern route around the Misty Mountains. It is 10 miles wide. Its location and size makes it both easy and important to control.
Next, moving south, is Rivendell - the home of Elrond and one of the more important elven realms. Rivendell was located on the western side of the High Pass. Technically, there are two passes in this area, but one was quite prone to orc attacks. This is partially due to the fact that under this pass was Goblin Town.
Moria is not too much further south. The Redhorn Pass (or gate) runs along the Caradhras mountain. This is the most southern pass through the Misty Mountains. Elrond's wife was captured by orcs on it. The hobbits moved to the Shire by crossing it. After Moria fell to the Balrog, mainly elves used this path. Most famously, this is the path that was so treacherous that it forced the Fellowship into Moria itself. Gimli describes the mountain itself as a maleviolent force. On the eastern side was the Dimrill Dale - a valley that the Redhorn Pass comes into. A series of waterfalls comes down into the Dale known as the Dimrill Stair. This then leads to Lothlorien.
The range ends just north of the White Mountains at Methedras. The area separating the two ranges is the Gap of Rohan and the location of Isengard. Fangorn is next to this. The Entwash River originates here, providing an important source of water and key geographic feature for both the ents and Rohan.
All that to say that the Misty Mountains were quite difficulte to travel through. People had a few dangerous options or had to go around. The only real option in the general area was Moria itself - 15-20 miles to the south. In fact, the difficulty of the Redhorn Pass motivated the construction of the Western Gate. After all, if one wishes to trade with people on the western side, the Redhorn Pass would be a major problem. But when Moria closed down, this option was lost.
J. R. R. Tolkien (1954), The Fellowship of the Ring, 2nd edition (1966), George Allen & Unwin, book 2 ch. IV p. 311; ISBN 0 04 823045 6
The Gladden River originates in the central Misty Mountains. Isildur was ambushed murdered in this river. Smeagol found the One Ring and murdered his cousin while fishing in it. He then followed the river to the natural caves in the Misty Mountains, where he lived near the resident goblins. Here is where Bilbo would find the One Ring.
It must be noted that the Gladden River was also an important region in the eventual betrayal by Saruman. After a meeting of the White Council, he began looking for the One Ring in this region - at this point for his own purposes. During this search, he became alarmed that Sauron's agents were also looking in the same region. I would imagine that this was the first point of contact that facilitated the alliance between Isengard and Mordor.
Underneath the Misty Mountains is a sort of underworld. Many natural undground lakes, streams, caves and tunnels. This is where the Watcher in the Water comes from. The middle of Gandalf's fight with the balrog occurs here. Goblin-town under the High Pass existed at this level, with its many mines, slave pits and torture chambers.

Fauna & Flora

One of the major locations of eagle habitat is the Misty Mountains. Most of the eagles we meet in the Hobbit and Lord of the Rings I think live here. The eagle eyrieis located on the eastern side of the range. By the time of Lord of the Rings, the elves are the only humanoid species resisting Mordor in the area. The dwarves have been forced out.
The most obvious evil inhabitant is Durin's Bane - Morias resident balrog. Orcs and trolls reside all along the range as well. Orcs from Moria and Gundabad did take part in the Battle of Five Armies. The utter destruction of the orc army in that battle and the fact that so many orcs took part led many to believe the Misty Mountains were free of orcs. This proved to be devestingly wrong when Balin's colony in Moria was wiped out. The Fellowships belief in this made their life more difficult as well.
These orcs appear to be mostly independent of Mordor. Sauron did send proxies to control them. That control appears to be more intermittent, indirect and covert. They tended to just go about their normal raiding and violent attacks. Often, this meant battles with the Rangers of the North - which by the time of Lord of the Rings meant Aragorn. After the War of Dwarves and Orcs, many of the Orcs of the Misty Mountains fled to the White Mountains, where they focused on harassing Rohan.
Now, The Hobbit states that 3/4ths of the orc population of the Misty Mountains was killed in the Battle of Five Armies. The book numbers of that battle was between 10,000-25,000 orcs, wargs and bats. Thus no specific numbers that I could find on just orcs. But the movie battle has those specific numbers 40,000 total orcs. We can therefore assume that the maximum population of orcs in the Misty Mountains was 55,000 and dropped down to between 3,500 and 13,333 after the battle. The Battle of Five Armies thus was a huge impact on the balance of power in the Misty Mountains.
The combination of all these setbacks meant that Isengard and Mordor became growing influences. Not only were their losses great enough to make them easier to control, both Saruman and Sauron saw their own power rise at the right time to exploit this trend. Mordor exerted its influence over the survivors who returned to Moria. Meanwhile those that fled to the White Mountains became under Isengard's control. Their presence provided another force to aid in the war against Rohan, plus a suitable labor force to help get the armaments program started. Most importantly, it was these orcs that helped Isengard attack the Fellowship and escort Merry and Pippen back to Isengard.
Other important residents include bears and giants.

Natural Resources

Its mineral deposits make it a valuable territory to hold.

Type

Mountain Range

Included Locations

• Moria
• Rivendell