Situated in the heart of Scotland, and having around it tribes of different races, and subsequently the four kingdoms of the Picts, the Scots, the Angles, and the Britons, surpassing the other districts in fertility, and possessing those rich carses which are still distinguished as the finest agricultural districts of Scotland, this region was coveted as the chief prize alike by the invaders and the native tribes. The scene of the principal Roman campaigns, it appears throughout the entire course of Scottish history as the main battlefield of contending races and struggling influences. Roman and Barbarian, Gael and Cymry, Scot and Angle, contended for its occupation, and within its limits is formed the ever-shifting boundary between the petty northern kingdoms, till in the memorable ninth century a monarchy was established, of which the founder was a Scot, the chief seat Scone, and that revolution was accomplished, which it is difficult to say whether it was more civil or ecclesiastical in its character, but which finally established the supremacy of the Scottish people over the different races in the country, and led to their gradual combination and more intimate union in the subsequent kingdom of Scotland. The kingdom of the Scots soon extended itself over these central plains. Its monarchs usually had their residence within its limits, and the capital, which had at first been Scone, on the left bank of the Tay, eventually became established at Edinburgh, within a few miles of its southern boundary. During the few succeeding centuries of Scottish rule, after the establishment of the Scottish monarchy in the ninth century, it remained limited to the districts bounded by the Forth on the south, the mountain chain called Drumalban on the west, and the Spey on the north. The Scots had rapidly extended their power and influence over the native tribes within these limits; but beyond them (on the north and west) they held an uncertain authority over wild and semi-independent nations, nominally dependencies of the kingdom, but in reality neither owning its authority nor adopting its name. It was by slow degrees that the peoples beyond these limits were first subjugated and then amalgamated with the original Scottish kingdom; and it was not till the middle of the thirteenth century, when the annexation of the Western Isles by Alexander the Third finally completed the territorial acquisitions of the monarchy, that its name and authority became co-extensive with the utmost limits of the country, and Scotland was consolidated in its utmost extent of territory into one kingdom. [Sidenote: Periods of its history.] The early history of Scotland thus presents itself to the historian in five distinct periods, each possessing a character peculiar to itself.