Chapter One: Realms ruled by the house of Finarfin
The realms ruled by the house of Finarfin were the largest set of lands ruled by any house of the Noldor. The realms consisted of Nargothrond, Dorthonion, and the Pass of Sirion.
Part One: Nargothrond
When Nargothrond is mentioned nowadays, one first thinks of the great city of Nargothrond which was located in the caves beneath the High Faroth beside the river Narog. This was the realm's capital, but the realm of Nargothrond extended over a surprisingly large portion of Beleriand, stretching from the river Teiglin to the river Nenning, and south from the Pass of Sirion to the sea, with the exception of the Falas, with whose lord, Cirdan, they were allied. The heart of the realm was the Talath Dirnen, or guarded plain. The soil of the Talath Dirnen was extremely fertile and well suited to growing crops.
The range of hills in which the city of Nargothrond was located were composed primarily of limestone. The combination of limestone and water resulted in caves which the petty dwarves then extended for their own use, and the elves after them. This was noticeable not only with regard to the city to Nargothrond itself, but also in the fact that the river Sirion disappeared underground for many miles not far away. The river's disappearance was known as the Falls of Sirion, and was very spectacular to look upon. The topography of this area was primarily karstic, and was characterized by many sinkholes and small lakes. The water was hard and somewhat alkaline.
The Talath Dirnen was the bread basket not only of Nargothrond, but of all the Noldorin realms. Hithlum was partially dependent on Nargothrond for grain, which did not grow very well in Hithlum's cold climate. The Talath Dirnen was very fertile and most crops grew well. As the soil was somewhat alkaline, crops requiring acidic soils needed special care or would not grow at all. In particular, blueberries could not be grown without using sulfur or large amounts of imported peat.
In addition to farming, many crafts were practised in Nargothrond. The large population lent itself to the practice of specialised skills, so difficult to create manufactured goods were among Nargothrond's exports. However, until the arrival of Celegorm, Curufin and their people from Himlad, the method of making Feanorian lanterns was unknown in Nargothrond, and these lanterns were one of Nargothrond's most expensive and vital imports.
Peoples and population
The population of the realm of Nargothrond included both Noldor and Sindar. The two peoples had become mixed, but the Noldor tended to be concentrated in the city of Nargothrond and the major fortresses, while the villages were predominantly Sindar. There were also often a few individuals of other peoples living in Nargothrond, including dwarves, humans, Nandor and Avari, although none of these made up a significant portion of the population. An example of such an individual would be the human Beor, who lived there for approximately 40 years.
It is not certain now what proportion of the population was Sindar and what was Noldor, but it is believed that well over half the population was Sindar, and that the total population may have been around 100,000. Population estimates are complicated by the fact that Finrod was considered the overlord of all the Sindar in western Beleriand, many of whom were nomadic; an influx of refugees after the Dagor Braggollach; and by an almost total loss of written records during the destruction of Nargothrond.
Nargothrond was governed by King Finrod Felagund, who owed fealty to the High King of the Noldor. After Finrod's death, Nargothrond was ruled by his nephew Orodreth. Nargothrond was destroyed when Orodreth died, so he had no successor. Individual settlements had councils which advised the king in the case of the city of Nargothrond, a representative thereof, or in the case of many of the more remote villages ruled the settlement outright.
Alliances and Foreign Policy
Nargothrond was a hidden kingdom. While it was not possible to completely disguise where the realm itself lay, the whereabouts of the capital city was a closely guarded secret. This was done primarily by preventing any of Morgoth's spies from returning alive from the realm, and by swearing all who know the whereabouts of the city to secrecy. In this the name of the city was unfortunate, as it strongly indicated that the city lay along the river Narog in a region containing caves, which must have pointed Morgoth towards the region near the High Faroth. Still, the vigilence of the people of Nargothrond prevented Morgoth from getting the detailed information he needed to attack it for a very long time.
Fluctuations of foreign policy, such as occurred during Celegorm and Curufin'susurpation of power and Turin's sojourn in Nargothrond are discussed in great detail elsewhere 1), and need not be discussed further here.
Nargothrond was allied with the elves of the Falas. One of the side-effects of this alliance was that Gil-galad, son of Orodreth, spent much of his childhood there as a refugee from the wars with Morgoth, and political troubles involving the Feanorians. This proved to be important for intra-Elvish relations during the Second Age.
1) for more information on foreign policy fluctuations, please see the Lay of Leithian, the Narn i Hin Hurin, and Erestor's voluminous Politics and Policy in Beleriand.