Syrmia County shared borders with other Croatian-Slavonian counties of Požega and Virovitica, the Austro-Hungarian land of Bosnia and Herzegovina, the Kingdom of Serbia, and the Hungarian counties of Bács-Bodrog and Torontál. The County stretched along the right (southern) bank of the river Danube and the left (northern) bank of the river Sava, down to their confluence. Its area was 6,866 km² around 1910.
By the 13th century, two counties were formed in this region: Syrmia (in the east) and Vukovar (in the west). Syrmia County was an administrative division of the Kingdom of Hungary in the Middle Ages. This area was taken by the Ottoman Empire in 1521 and the two counties were abolished. The territory was then (in 1544) included into Ottoman Sanjak of Syrmia. The Habsburg monarchy took one part of Syrmia from the Ottomans in 1688, while the other part was taken by Habsburgs in 1718. The entire region was incorporated into the Military Frontier, which was then extended from Western Slavonia, where it stood in 1683, all the way to Transylvania.
History
For the history of the general region of Syrmia, see Syrmia.
After 1860, Syrmia County was established again, and was reincorporated into the Kingdom of Slavonia, which was a completely separate Habsburg province at the time. In 1867, as a consequence of the Ausgleich between the Austrians and the Hungarians, the Kingdom of Slavonia was incorporated into Transleithania, the half of Austria-Hungary run from Budapest, and in the Hungarian-Croatian Settlement of 1868, it was incorporated into Croatia-Slavonia, a formally separate kingdom within the Kingdom of Hungary, which had a certain level of autonomy and was ruled by its own ban.
In 1881 the Slavonian Military Frontier was abolished; the Petrovaradin district and part of the Brod district would be merged into Syrmia County by 1886.