The concept of a Serbian Vojvodina as a political and territorial unit, was present among the Serbs in the Habsburg Monarchy from the end of the seventeenth century until the First World War. During the period it existed (1848–1861) or when demands for it again emerged (before 1848 and after 1861) the question of its borders arose. This became especially apparent when the people in Vojvodina voluntarily joined the Kingdom of Serbia, which subsequently became a newly formed state for Serbs, Croats, and Slovenes in December 1918. When a common state was created, the issue of Vojvodina's borders centered on its northern borders, which were defended at the Paris Peace Conference according to historical and ethnic principles.