In the mountains around Nord-Gudbrandsdalen there are at least fifteen sites where herds of reindeer were trapped in a mass trapping system. The reindeer were chased towards the traps, which were mainly built of converging wooden fences, leading into a stall where the animals were captured and killed. Some of the sites are thought to have accommodated several hundred reindeer. Stalls that were built with a wall of stone are well preserved today. At two other sites the animals were simply driven into a deep canyon and a lake, and killed there. The mass trapping sites are mainly located near the valleys with settlement or farms, but are also built close to a migration route used by the reindeer. It was also important to construct the traps in terrain which hid the fences and stalls, encouraging the animals to see the trap site as an easy route to escape from the people behind. Mass trapping systems around Nord-Gudbrandsdalen are mainly dated between 900 and 1300 AD. None are known after 1300 AD, suggesting this method of hunting had stopped by this time. Mass trapping seemed to be organized by many people, and the profits were certainly high, when the stock of reindeer was good. We believe this was almost like an industry, and that it was organised and supervised by the king or local chieftains. The reason of catching so many reindeer at the same time in one place was clearly to get valuable products to use in trade (see “vedlegg 5”) Skin and antler were popular products in Europe. Dried meat and fat from the animals could also be exported. The mass trapping sites share similarities with each other, but all sites are also unique. One important question is if the construction changes through time. It is possible that earlier sites have a simple construction, with later sites larger and more complex. Some of the biggest traps have corrals that could have kept the reindeer alive for many days, allowing the people to slaughter the animals over a longer period of time.