When considering the Clearances, it's always important to reflect that they mean very different things for different people and groups. But to start, here's some figures which demonstrate the impact which the Clearances had and still continue to have in many ways on Scotland:

In 18th century Scotland, one-third of the people lived in the 'Highlands'. Today, it is a mere 5%.

In 1811, there were a quarter of a million sheep in the Scottish Highlands - there were one million just 30 years later.

By the 1880s, a tenth of Scotland's land area was being used for deer forestry. For contrast, this area is greater than Wales' total area and most of this came from small crofting communities,

On the face of things, these two latter points may not seem to reveal much, but they signify the intensity of the change and the motive of it - landlords wishing to exact a sweeping land reform programme (at the expense of tenants).

Though the conflation of Culloden as the kickstarter of the Clearances is not correct, following Culloden was an immense upheaval in Highland life, which precipitated the events of the Clearances. For example, The Duke of Argyll chose to lease his lands to the highest bidder - and not the Campbell clansmen he chiefed, because of the abolition of feudal rights and disarmament of the Highland nobility. A minor change, but telling of how quickly British powers had destabilised clan culture, one tenet of a vivid highland culture.

Indeed, initially after Culloden, population grew in the Highlands off the back of newly formed townships - on 'common land'. Landlords in the Highlands evicted tenants from arable land onto so-called common land - creating townships; based on the idea that crofting alone was not enough to sustain a family and so workers would need to seek employment from the landlord to do so. Tenants would, of course, be reluctant to improve their plot of land where possible, as that would often tempt a princely increase in rent.

Towns like Ullapool appeared, buoyed by the consumption of the Napoleonic Wars. But, in peacetime, demand for kelp and beef decreased, which coincided with a collapse in the herring catch. Returning from war were thousands of young men and with them, the delicate economies of the region buckled. Potatoes, easy to grow, were introduced in the Highlands and they were to become the basic staple for many people.

Larger, more lucrative sheep were shipped from the lowlands by landlords for their large sheep farms. These bigger sheep were placed on a greater amount of arable land, pastures which would have previously been used by Highlanders to rear their cattle and smaller breeds of sheep.

The above mentioned economic downturn meant landlords would resolve to removing crofting as much as they could, and turning to sheep grazing. Infamously, in the Countess of Sutherland's Highland estate, Lord Stafford had removed 6,000-10,000 tenants between 1807 and 1821. In cases like this, crofters were offered resettlement in nearby towns or emigration, and many young Scots opted to relocate to Canada, for instance.

A factor which exacerbated the turmoil was the dislike of the Highland Scots by those in the Lowlands. As Robert Knox (famous for his business with Burke and Hare) wrote in The Races of Men (1850), 'The Anglo-Saxon race' was superior to the Highlanders, who he said "must be forced from the soil'. Indifference to, or support for, the suffering of Highland Scots was predictably forthcoming.

Now dependent on the potato, anxiety emerged in 1846 after a potato blight made famine a possibility in the Highlands. Throughout this perilous time, the Clearances continued.

TL;DR:

• Landlords begun to see that they could profit through means other than renting to crofters, e.g. sheep grazing

• The economy was too volatile for people to be able to make a living, especially with landlords trying to preserve their own power

• Poor harvests and crop failures

• A lesser discussed aspect - people were persuaded by suave transatlantic ferry salesman and voluntarily chose to move to countries like Canada and the United States

• A resentment of Highlanders by those in the Lowlands stopped any real intervention to stop the Clearances

Source: Bambery, C. A People's History of Scotland (2014)