I first guessed it had something to do with the Versailles Treaty.
On googling the image, I found it was a 1918 picture of the declaration creating the Kingdom of Serbs, Croats and Slovenians, later known as Yugoslavia.
Yugoslavia lasted about as long as the Soviet Union, notably interrupted by WW2, when it was split up and occupied by Axis forces.
After the war, Yugoslavia was held together for decades mostly by the prestige of Marshal Tito, but after his death in 1980, the old internal troubles between the member states of Yugoslavia once again came to the fore.
On googling the image, I found it was a 1918 picture of the declaration creating the Kingdom of Serbs, Croats and Slovenians, later known as Yugoslavia.
After the war, Yugoslavia was held together for decades mostly by the prestige of Marshal Tito, but after his death in 1980, the old internal troubles between the member states of Yugoslavia once again came to the fore.