Helm then proclaimed Freca’s son and near kin the king’s enemies; and they fled, for at once Helm sent many men riding to the west marches.
- Appendix A, The Annals of Kings and Rulers
The westernmost region of the kingdom of Rohan, the West-march (or the West Marches) have held a unique position throughout the kingdom's history. Situated on a triangular peninsula between the rivers Isen and Adorn, it is only connected to the rest of Rohan by a small road along the feet of the White Mountains. Its largely isolated position paired with its strong Dunlendic heritage have made its loyalty to the Kings of Edoras dubious throughout the region's history.
This was most notably the case when Wulf, Lord of the West Marches, rebelled against King Helm Hammerhand in T.A. 2758. Together with his Dunlending allies, he invaded the other parts of the kingdom in an attempt to crown himself king. Although he managed to drive King Helm to Helm's Deep and capture Edoras, his rebellion ultimately failed after the Long Winter of T.A. 2759.
He grew rich and powerful, having wide lands on either side of the Adorn. Near its source he made himself a stronghold and paid little heed to the king.
- Appendix A, The Annals of Kings and Rulers
The West-march is the westernmost region of Rohan and its only region west of the White Mountains. It is only accessible by a small road between the river Isen and the feet of the mountains. The largest part of the region is made up of a triangular peninsula between the Isen and the Adorn, the latter of which arises in the mountains on the region's eastern border.
This peninsula can be divided into an eastern and western half. The eastern half consists of a highland, largely covered in forests. It has been settled for many centuries. The lowlands that constitute the region's western half, on the other hand, have only been settled in recent years. The most recent of these settlements is the village of Aberrhyd.
Significant seasonal differences between warm to hot summers and cool to cold winters are the main feature of the region's climate. Both temperatures above 30°C for the summer months and air frosts during winter are common. In addition, the climate is much gloomier than in the regions south of the White Mountains, although less so than in Dunland.
Rainfall is quite heavy compared to other regions of Rohan, although the number of rainy days is relatively moderate. As a result of winter lows averaging below freezing, snowfall also occurs, although the the region's climate is too mild to sustain a snowpack all winter, unlike the surrounding mountains.
The West-march is ruled by a Thegn (or Thane) sworn to the King of Rohan. The region's isolated position grants its ruler much independence. The Thegn resides in Isenwick and is responsible for the governance and defense of the region. His subjects pay him tribute in the form of produce and other valuables. The current Thegn is Idelgeorn, an old man who has very little interest in governing.
Most of the day-to-day ruling is given to the six Aldermen, powerful men who act as the Thegn's counsel. The most important of these is Ealdwulf, of the lineage of Wulf. A shrewd politician, he has amassed much wealth in recent years and betrothed himself to the Thegn's daughter. Though he resides in Carrdun, he is rebuilding his ancestral fortress in the region's southeast with the help of stonemasons from Isengard.
At the same time Rohan was again invaded from the East, and the Dunlendings seeing their chance came over the Isen and down from Isengard. It was soon known that Wulf was their leader.
- Appendix A, The Annals of Kings and Rulers
Culturally, the West-march is characterized by its mixed Dunlendic and Rohirric identity. While the eastern parts of the region are more closely tied to Rohan and its culture and customs, the western parts of the region remain mostly Dunlendic. This divide is not only expressed in beliefs and customs but also in architecture. While longhouses are more numerous in the east of the West Marches, its western and southern settlements are almost entirely comprised of Dunlendic roundhouses.
The West-march’s strong connection to Dunland and its people extends to religious beliefs. Similar to the Dunlendings, the people of the West-March believe in a wide pantheon of deities, including some major gods that are common across the land as well as minor, local spirits. There are no direct visual depictions of these deities, only symbolic representations. Druids are the leading religious figures and live in almost every larger West-march settlement. They may have a particular devotion to a local god, but more often they are universal in their practice.
The West-march's mixed cultural identity also impacts its economy whereby it represents a middle ground between the more primitive Dunlendings and the more technologically advanced Rohirrim. The vast majority of the West-march’s inhabitants are farmers and herdsmen. Its industries, such as weaving, woodworking, and tanning are often limited to individual homes and local use.
The region's geographic isolation further limits its possibilities to engage in trade. Although trade with the eastern parts of Rohan remains important, the past conflicts between the two have left their mark. In recent years, trade with Isengard has become more and more prevalent as the wizard Saruman continues to expand his sphere of influence.