State of Slovenes, Croats and Serbs
At the end of World War I, the Austro-Hungarian Empire collapsed. On 29 October 1918, Syrmia became a part of the State of Slovenes, Croats and Serbs. On 31 October 1918, the Banat Republic was proclaimed in Timișoara. The government of Hungary recognized its independence, but it was short-lived.