Two years ago more than 47,000 people from all over the world journeyed to Scotland to celebrate their Caledonian lineage in an event called the “Homecoming”. Many of them had only recently discovered an interest in their origins and some, it seems safe to say, held peculiar ideas about where their forebears had come from and what impelled them to leave. Many people of Scottish descent, especially in America, assume that their ancestors hailed from the Highlands; that having been dispossessed of their land, they were forcibly driven into exile; and that after the Jacobites’ defeat at the battle of Culloden in 1746, if not before, these brave, egalitarian and freedom-loving people were victims of the oppressive English.

The truth is more complicated than that, as T.M. Devine, a professor of history at the University of Edinburgh, is at pains to show. The Scots have been emigrants and adventurers since at least the 13th century. At first most went to northern Europe as mercenary soldiers or traders, setting up commercial networks from Rotterdam to Königsberg and penetrating far into Poland. Later they settled in large numbers in Ulster. By the beginning of the 18th century life expectancy was rising among landed Scots but second and third sons had little hope of becoming farmers.

For many of these, the Act of Union with England in 1707 came as a blessing. It opened to Scottish merchants the protected markets of the English colonies and provided countless jobs for soldiers, contractors and bureaucrats in an expanding empire. For Presbyterians, the union also had the political advantage of providing a defence against the possibility of an unwelcome Catholic Stuart restoration.

Scots, already well established in the Caribbean, were soon all over British North America and, through the East India Company, much of Asia. Scots were prominent in trading firms like Jardine Matheson and the North West Company; in 1799, 78% of the overseas employees of the Hudson’s Bay Company, whose domain encompassed more than 10% of the Earth’s land surface, came from the islands of Orkney alone. Scottish emigrants flourished not only throughout the empire but also in England, other parts of Europe, and even South America and Japan.

Many of those who stayed at home also prospered. By the 1770s Glasgow had secured most of the British tobacco trade. It later became a centre for sugar, engineering and shipbuilding. All over the country fortunes were being made in textiles or related products. In Dundee the product was jute, in Paisley it was thread, in Kirkcaldy carpets. Scotland also became a leader in railways, chemicals, locomotives and then finance. No wonder that by the 1850s it was one of the most urbanised and industrialised countries in the world.

Why then did it send so many of its citizens abroad? The answer varies according to time and place of origin. Emigrants came from all over the country. Some, particularly in the Highlands and islands, were certainly poor, even destitute, and the clearances in the late 1840s and early 1850s were undeniably brutal and often coercive. Most of those who left, however, were not utterly impoverished; many had skills and qualifications. Some were driven by martial spirit, missionary zeal or imperial fervour. The empire, Mr Devine points out, was an emphatically British venture in which the Scots saw themselves as equal partners with the English, giving them self-respect as well as prosperity.

The main motive, though, was the desire for a better life and more opportunities. In this, and in their readiness to work hard, Scots were much like emigrants elsewhere. Similarly, like other emigrants, they persecuted native Americans, exterminated aborigines, stole land, defrauded their partners, exploited their workers and happily traded in opium. They did not trade in slaves, not much anyway. But Scotland’s economy in the 18th century was inextricably intertwined with slavery through the sugar, tobacco and cotton industries, plus the civil and military structures that sustained them. Scots were pretty average in other ways, too. They made bad investments, could be thoroughly prejudiced (often about each other) and, it should be remembered, frequently returned home as failures (over 40% in the 1890s).

Yet in some ways they were untypical. They were often educated, which helped to account for the high numbers of lawyers, doctors and engineers among them. This in turn may explain why they were so influential in the lands where they settled. They were also militaristic, religious (David Livingstone, still revered in Africa, became a Victorian saint), loyal (notably to the Crown in the American colonies) and liberal (reflecting the Scottish Enlightenment). Above all, they were numerous, at times proportionately more so than any European nation except the Irish and perhaps the Norwegians.

Mr Devine explains all this with a masterly breadth of knowledge and an admirable absence of hyperbole. Unfortunately, his editors do not match his skills. The inclusion of so much analysis of Scottish topics and Scotland’s engagement with the world shortchanges those expecting a comprehensive book about the emigrants themselves. Moreover, the reader may weary of so many repetitive statistics. Most could have been incorporated in a single chart or map showing how many Scots left when, where they came from and where they went. All these blemishes, however, count as little compared with the work’s great virtue of helping to rescue Scottish history from the romanticised, self-pitying, tartan tosh that has captured the popular imagination of so many Scots both at home and abroad.