The evidence for the period of initial Viking incursions from the 9th century onwards in Caithness is surprisingly slight. The surviving evidence, particularly from graves and artefacts, suggests that the earliest dating we have in the county is around the 10th century. The limited number of excavated settlements all appear to date to after this period. However, there can be little doubt that Caithness was a crucial area for Norse activity throughout the 9th and 13th centuries. There will have been many Norse farmsteads, the farmhouse typically a long building with a byre in one end. Place names also show something of the extent of the areas once inhabited by the Norse people. Some castle sites, such as Castle of Old Wick and Buchollie, have, through tradition, been attributed to the later Norse period, around the 12th / 13th centuries, although this is impossible to prove without excavation.