The territory of the Caledonians lay from Loch Long eastward to the Firth of Tay and the German Ocean, and northward in later times to the Moray Firth. The Caledonian Forest is represented as extending in a north-eastern direction from Loch Lomond to the river Isla. The Caledonian territories, however, were always shifting. Like the _Celtica_ of the Continent of Europe, the _Gaeltachd_ of the British Islands was always under a process of change, but at the same time it was ever the region or the land of the Gael. Lands were won from the tribes whom the Gaels conquered, while territories were surrendered to those who pressed on behind them. At first the _Gaeltachd_ was in South Britain; but as the Gaels moved northward, Albin contracted, and the land of the Gael extended. Finally, the Caledonians became the general term for all the Gaelic clans who opposed the legions of Rome. The etymology of _Caledonia_ has not been satisfactorily explained. The celebrated James Macpherson explains it as follows:—“When South Britain yielded to the power of the Romans, the unconquered nations to the north of the province were distinguished by the name of _Caledonians_. From their very name, it appears that they were of those Gauls, who possessed themselves originally of Britain. It is compounded of two Celtic words, _Gael_, signifying _Celts_ or _Gauls_, and _Dun_ or _Don_, _a hill_; so that _Gael don_, or Caledonians, is as much as to say _Celts of the hill country_.” In the very next sentence Macpherson unconsciously suggests quite a different and better etymology: “The Highlanders to this day call themselves _Gael_, their language _Gaelic_ or _Galic_, and their country _Gaeldoch_, which the Romans softened into _Caledonia_.” Consideration for Latin Inflections would readily transform _Caeldachd_ into _Caledonia_. A rival explanation has found place in many school books—Coille-daoine, rendered _Men of the Wood_. This, however, is not the accurate translation. The compound is absurd and unnatural. It reads to a Gael like _Men-Wood_ in English. Another explanation has been _Gaedhil dhonna_, brown-haired Gaels; but physiological facts and the laws of phonology do not support this derivation. The Welsh have given us its meaning from a Cymric standpoint; and as the word is unknown in Gaelic in its historic form the Welsh suggestions appear very reasonable. The Caledonian Forest in Welsh has always been Calydin or Celydin, a term which means _Wood_. Its Gaelic cognate would be _Coilltean_, which also supplies the representative consonants of Caledonia. The great forest of the Central Highlands would be very naturally spoken of as the _Woods_, Coiltean; _Caledonii_ being only a Latin derivative.