With the exception of Blanchard, Deffontaines, Derruau and Hamelin, few geographers have studied the rang, in particular its origin. Among the more recent studies are those of Harris and Belanger. The former suggests that the rang could have developed independent of the land holding System, while the latter believes that it grew out of natural and social factors of regional organization. The aim of this article is to shed light upon the context into which the rang appeared in the Saint Lawrence Valley. The hypothesis is that the seigneuries and the rotures defined an original System of land parcelling in order to advance a rapid and total occupation of the laurentian corridor, the major route towards the interior. Begun during the first half of the XVIIth century, the implantation of the rang was sufficiently established by 1663 to resist any future political changes.