The terms landwehr ("land defence"), landgraben ("land ditch") and landhege ("land enclosure") refer to border demarcations or border defences and enclosures in Central Europe that were either built by settlements with the right of enclosure or to mark and defend entire territories. These measures, usually comprising earthworks or dykes as well as ditches and impenetrable lines of hedging, for protecting towns and villages date mainly to the High and Late Middle Ages and consist, in some cases, of systems over a hundred kilometres long. Comparable earthworks have been recorded since Antiquity. The Roman limes are the best known examples of earlier landwehrs. The Danewerk is another example of this type of barrier.

Many of these landwehrs have survived, especially in woods and forests, and are often protected as heritage sites.

The construction of a landwehr was an effective way of protecting the population of a settlement or territory against attacks by neighbours or enemies in feuds or war, and also to mark out the legal limits of an area. The landwehrs were a means of limiting the likelihood, success, effectiveness, and consequences of medieval warfare, and thus preventing them. They also hindered bands of robbers entering the area and hampered their retreat after a raid. The combination of fencing and thorn bushes was also useful in enclosing cattle pasture and as a guideline in wolf hunting. Wolf pits are often found along the line of a landwehr.

Landwehrs were also used to on a large-scale to enclose woods and agricultural areas for the protection of the local population, where they were settled in dispersed dwellings and farmsteads within the protected area. The landwehr offered protection for the peasantry, in a way analogous to the population of fortified towns who were guarded by a town wall. Often too, the fields and outlying areas surrounding many towns had a ring-shaped enclosure, a so-called Stadtlandwehr ("town Landwehr"), Stadthagen or Stadthege ("town enclosure"). An example of this is the Westphalian city of Dortmund, which, in addition to the city wall, also had a large landwehr surrounding it. As a map of 1748 portrays, Dortmund's Stone Tower was part of this landwehr ring.

The only gaps in landwehr defences were on roads entering the area where, like the gates in a town wall, people and goods were checked as they passed through. For example, landwehrs often acted as effective customs posts, usually imposing a road toll.

Trade routes, particularly in the area of check points, were accompanied on both sides by landwehrs. In addition to protecting travellers from ambushes, these landwehrs on either side of the route were mainly used to channel the flow of traffic and effectively prevent people bypassing or avoiding check points and customs posts.

Hedges are one of the most natural forms of boundary defence and enclosure. Their simplest and, even today, most common use is as a garden hedge. Even in prehistoric and early historic times, people built defensive enclosures using branches and brambles for the protection of storage places (including caves), fortified residences, houses, estates and settlements from attack by predators or enemies. This is common even today amongst nomadic tribes. Julius Caesar tells e.g. of thick Hagen which were laid out by the Nervii, one of the most powerful Belgic tribes:

Having no strength in cavalry (for even to this day they care naught for that service, but all their power lies in the strength of their infantry), the easier to hamper the cavalry of their neighbours, whenever these made a raid on them, they cut into young saplings and bent them over, and thus by the thick horizontal growth of boughs, and by intertwining with them brambles and thorns, they contrived that these wall-like hedges should serve them as fortifications which not only could not be penetrated, but not even seen through.