[1] Bulgarian revolutionary Georgi Sava Rakovski was provided shelter in Belgrade, revolutionary publications were printed in the city and Rakovski's armed group joined clashes against Ottomans in Belgrade in 1862.

The Bulgarian side proposed the founding of a common Serbo-Bulgarian (Bulgaro-Serbian) dual state called South Slav Tsardom, headed by the Serbian Prince.

Serbian Prime minister Ilija Garašanin accepted the Bulgarian proposal in a letter from June 1867, but he diplomatically refused to sign the document, fearing how representative this organisation had been.

[3] The establishment of this common state concerned other Bulgarian organisations, which perceived it as an implementation of Garašanin's plan called Načertanije.

[6][7] Serbian Presidents Aleksandar Vučić and Bulgarian PM Boyko Borisov concluded that the opening of the Balkan Pipeline through Bulgaria and Serbia in 2021 was a "remarkable success of the two fraternal states".