The Scottish Highlands is an historic region of Scotland. It is the area to the north of the Highland Boundary Fault. The fault separates the hard igneous and metamorphic rocks to the north from the softer sedimentary rocks of the Scottish Lowlands in the south.
Before the 19th century the Highlands was home to a much larger population but, for several reasons, the area is now one of the most sparsely populated in Europe. The average population density in the Highlands and Islands is lower than that of Sweden, Norway, Papua New Guinea and Argentina.
The reasons for the low population include the harsh nature of the land. Also, the outlawing of the traditional Highland way of life after the Jacobite Rising of 1745, the infamous Highland Clearances, and mass migration to urban areas during the Industrial Revolution all had their effects.
Like the Scottish islands, the Highlands are a stronghold of Protestant churches. There is the Kirk (the national Presbyterian Church of Scotland), but the Wee Frees (Free Church of Scotland, several versions) are the typical religion of the Highlands and Islands. Old-style observance of the Sabbath is typical of these areas.