It is true, when a surplus population compelled them to send abroad swarms of their youth, that the conquest of a foreign country became an absolute necessity. But, on such occasions it was outside of Celtic limits that they spread themselves, taking possession of a territory not their own. They almost invariably respected the land of other clans of the same race, even when most hostile to them; exceptions to this rule are extremely rare. It was thus that they sent large armies of their young men into Northern Italy, along the Danube, into Grecian Albania and Thrace, and finally into the very centre of Asia Minor. The fixing of the geographical position of each tribe was, therefore, a rule among them; and in this they differed from nomadic nations, such as the Tartars in Asia and even the North American Indians, whose hold on the land was too slight to offer any prolonged resistance to invaders. Hence the position of the Gallic _civitates_ was definite, and, so to speak, immovable, as we may see by consulting the maps of ancient Gaul at any time anterior to its thorough conquest by the Romans; not so among the German tribes, whose positions on the maps must differ according to time. We have already seen that so sacred were the limits of the clan districts, that one of the chief duties of ollamhs and shanachies was to know them and see them preserved. But if territory was defined in Celtic nations, the right of holding land differed in the case of the chieftain and the clansman. The head of the tribe had a certain well-defined portion assigned to him in virtue of his office, and as long only as he held it; the clansmen held the remainder in common, no particular spot being assigned to any one of them. As far, therefore, as the holding of land was concerned, there were neither rich nor poor among the Celts; the wealth of the best of them consisted of cattle, house furniture, money, jewelry, and other movable property. In the time of St. Columba, the owner of five cows was thought to be a very poor man, although he could send them to graze on any free land of his tribe. There is no doubt that the almost insurmountable difficulty of the land question at this time originated in the attachment of the people to the old system, which had not yet perished in their affections; and certainly many "agrarian outrages," as they are called, have had their source in the traditions of a people once accustomed to move and act freely in a free territory.