Most of what we know about early Gaelic society is based on the contents of seventh and eighth century Old Gaelic Law texts from Ireland , like Críth Gablach , many of which only survive in fourteenth to sixteenth century copies. Therefore, the information they contain may have become corrupted in transmission over time. Nevertheless, it appears that early Gaelic society was tribal, rural, hierarchical and familiar. Tribal, because the basic territorial unit was the túath (usually translated as tribe); rural because there seem to have been few areas of dense settlement; hierarchical because society was strictly divided into ranks (each with their own honour-price), and familiar because society was kin-based. The most common kin-group referred to was the derbfine (true kin): descendants through the male line of a common great-grandfather, up to and including second cousins.
According to the law texts, the kin-group attached great importance to the principle of private land ownership. The word used for a unitary area of land was the cumal (originally meaning a female slave) and the value of a cumal of land varied: for example, good arable land was worth twenty-four milch cows and bogland was worth eight dry cows. When kin-land was being divided after a death, each male heir was provided with a share. A female could only inherit land (for her lifetime) if there was no brother. Although each landholder farmed as an individual, his kinsmen were able to control what he did with the land. No member of a kin-group could dispose of his share of kin-land without the agreement of the rest of his kinsmen, and kinsmen could be held responsible if one of their relations misused his portion of kin-land.
The rí (king) of each túath was assigned a portion of land and, in turn, could give some of this portion to his judge, poet, harper or doctor. All freemen of the túath owed loyalty to the rí and paid dues to him. The rí could summon them to a slógad (hosting) for either attack or defence. A rí could also owe loyalty to a ruiri (king of a few túatha ) and the rí would give hostages and tribute to the superior king. The law-texts also include a number of different grades of flaith (lord), the lowest grade of which must have ten céili (clients, who could also be kinsmen). Each lord advanced a parcel of land or stock to his clients in return for dues including food-rent, manual labour, military duties and hospitality. If a lord did not treat his clients justly, he could be reduced in rank.
In the Book of Deer there are two different names used to describe a unit of land: a pett or pit (estate) and a dabhach (a large vat, possibly a fixed amount of grain). One of these terms (pett), is definitely Pictish in origin and dabhach may also have originally been a Pictish word. However, despite these differences in terminology, it is likely that there were strong similarities in the social pattern of landholding in Ireland and Scotland . There is a lot of evidence relating to the granting of lands to members of the óes dána (men of learning) in Scotland , in return for professional services. Obligations on land, like common army service ( slógad ), became incorporated into the legal terminology of Scottish charters and continue to be used for a considerable period of time. Other evidence is found in the Book of Deer – for example, when Donnchad gave Auchmachar to the religious settlement ‘in freedom till Doomsday’, he may have been stating that he did not expect the monks to perform any dues – like food-rent or manual labour – in return for the grant of land.