Unlike today, premodern citizenship often concerned cities only and had little to do with the consolidation of boundaries between states. The transformation of the Habsburg-Ottoman frontier strip into a guarded border in the mid-18th century constitutes an exception from this pattern: there, migrant populations had to undergo a quarantine and to be officially registered. Beside having sanitary purposes, official registration allowed to determine the political subjectship of the merchants who practiced Orthodox rites. The identification process was based on written correspondence; it involved ever more people separated in space, a shift which changed the very nature of the process. Using ethnicity as a criterion for identification was an unknown practice in the western part of the Habsburg Monarchy, it was used only infrequently in the borderland, but it had become systematic when borders were crossed: clothing, which was a marker of social status in the Ottoman lands, became considered as a criterion to identify individuals and as an indication of political loyalty as early as the 1750s. This identification pattern, which was initially designed to register the merchants, eventually influenced the registration of rural migrant workers, on whom the ethnic criterion came to be used for the very first time in order to determine their local civic belonging a generation later. The way migrating peasants were sorted and land was allocated in a specific village was based on linguistic affiliation: it was the result of the combination of an old manorial management, policing concerns and of the new ideal of subject/citizen of the Habsburg State, inspired by the triumphant Cameralism.