The river Spey, which now separates the counties of Aberdeen and Banff from those of Moray and Nairn, was for three centuries the boundary between Scotia, or Scotland proper, and Moravia, or the great province of Moray. The Tay, which separates the districts of Stratherne and Gowry, formed for half a century the limit of the Anglic conquests in the territory of the Picts, and at the very dawn of our history interposed as formidable a barrier to the progress of the Roman arms. The Forth, which for three centuries was the southern boundary of Scotia, or Scotland proper, during the previous centuries separated the Pictish from the British population. [Sidenote: The debateable lands.] The tract of country in which the frontiers of several independent kingdoms, or the territories in the occupation of tribes of different race, meet, usually forms a species of debateable land, and the transactions which take place within its limits afford in general a key to much of their relative history. Such were the districts extending from the river Tay to the minor range of the Pentland hills and the river Esk, which flows into the Firth of Forth on the south. These districts fall naturally into three divisions. The region extending from the Tay to the river Forth, and containing part of Perthshire, was included in that part of the country to which the name of Alban, and afterwards that of Scotia, was given. The central district between the rivers Forth and Carron consisted of the whole of Stirlingshire and part of Dumbartonshire, and belonged more properly to Strathclyde. The region extending from the Carron to the Pentlands and the river Esk on the south comprised the counties of West and Mid Lothian, and was attached to Northumbria; but all three may be viewed as outlying districts, having a mixed population contributed by the neighbouring races.