Roman concept of dominium has been fundamental in the formation of concepts of ownership in European legal tradition. It is, however, often considered outside the context of Roman imperial rule and of the multiplicity of legal regimes governing property relations in Roman provinces outside Italy. This chapter starts from the classic passage in the Institutes of Gaius, claiming that the right of dominium did not exist in provincial land, where it belonged to the Roman state. Gaius’ statement is often dismissed in modern historical scholarship as a ‘conveyancer’s fantasy’ (A.H.M. Jones). It is argued here that, on the contrary, this passage and other similar statements in Roman juristic literature and technical literature on land-measurement, show an important facet of Roman ideas of ownership as a socially contingent right, dependent on civic status of the owner, status of the territory within the empire, and Roman recognition of local property regimes.