However, by 1843, "clearance" had become a general (and derogatory) word to describe the activities of Highland landlords. Its use was ambiguous, as for some it meant only the displacement of large numbers of people from a single place at one time. For others, the eviction of a single tenant at the end of a lease could be termed "clearance". Eric Richards suggests that current usage is broad, meaning "any displacement of occupiers (even of sheep) by Highland landlords". He adds that it can apply to both large and small evictions, and includes voluntary or forced removal and instances involving either emigration or resettlement nearby. T. M. Devine also takes the view that "clearance" has a broader meaning now than when it was used in the 19th century. Economic and social context Agricultural Revolution The first phase of the Highland Clearances was part of the Scottish Agricultural Revolution but happened later than the same process in the Scottish Lowlands. Scottish agriculture in general modernised much more rapidly than in England and, to a large extent, elsewhere in Europe. The growing cities of the Industrial Revolution presented an increased demand for food; land came to be seen as an asset to meet this need, and as a source of profit, rather than a means of support for its resident population. Before improvement, Highland agriculture was based on run rig arable areas and common land for grazing. Those working in this system lived in townships or . Under the run rig system, the open fields were divided into equivalent parts and these were allocated, once a year, to each of the occupiers, who then worked their land individually. With no individual leases or ownership of plots of land, there was little incentive to improve it (for instance by drainage or crop rotation systems). Nor, with common grazing, could an individual owner improve the quality of his stock. Enclosure of the common lands and the run rig fields was a method of improvement. More commonly, there was a greater change in land use: the replacement of mixed farming (in which cattle provided a cash crop) with large-scale sheep farming. This involved displacement of the population to crofts on the same estate, other land in the Highlands, the industrial cities of Scotland or other countries. The common view is that the shepherds employed to manage these flocks were from outside the Highlands. This is