The derbfine was a term for patrilineal groups and power structures defined in the first written tracts in early Irish law. Its principal purpose was as an institution of property inheritance, with property redistributed on the death of a member to those remaining members of the derbfine. Comprising all the patrilineal descendants over a four-generation group with a common great-grandfather, it gradually gave way to a smaller three-generation kinship group, called the gelfine.