In 1990-1995 he passed a post-graduate qualification at the same university, in the area of the History of Byzantium, and in 1995 Pirivatrić received a master's degree after defending of Master's thesis "Scope and Character of Samuil's state according to Byzantine sources", refuting the claims of Yugoslav and Macedonian historiographies about that state’s "Macedonian character" and acknowledging that it was the last stage of the existence of the First Bulgarian Empire.
Between 2001-2005, he was on a diplomatic service, and until 2003 he was First Secretary of the Serbia and Montenegro Embassy in Sofia, and until 2005 in Athens.
After 2005, Pirivatrić became a research associate at the Institute of Byzantine Studies and a lecturer at Belgrade University.
Author of some 50 scientific papers, published in Yugoslavia, Serbia, Bulgaria, Greece, France, Great Britain, Poland, Slovakia and Hungary.
[2] He was given an award in 2009 by the president of Bulgaria Georgi Parvanov for his contribution to the good relation between the Bulgarian and the Serbian people.