Older Mirko was, in 1898, known under the name Champion Globetrotter because he walked the distance between Paris, France and Saint Petersburg in Russia.
It is believed that the brothers started their journey after being impressed by the books or lectures by another Croatian explorer, Dragutin Lerman, who was in Africa as leader of Henry Morton Stanley's team.
There, on the recommendation of several influential Europeans, Menelik II, Emperor of Ethiopia provided them with an escort of 300 people to continue their expedition to the south.
They were highly regarded by the emperor Menelik II, and received many gifts, some of which are today in the possession of their families; some others are on display in the Ethnographic Museum in Zagreb.
In April 1903 the two brothers left for Rio de Janeiro in Brazil with the intention of entering areas that were at that time unknown, to establish traveling and trade routes and permanent posts.
They established Hrvatsko dioničarsko društvo (Croatian Brokerage Society) with the purpose of helping the government of Peru to plan, finance and build roads connecting two parts of the country, from the Andes to the Amazon basin.
The brothers took different paths for the first time in October 1912 with Stjepan heading toward the United States to initiate new business contracts, while Mirko was supposed to continue their research, starting a new expedition.
After his older brother's disappearance, Stjepan kept moving, searching for mineral deposits in South and Central America until, in 1917, he decided to settle and made his home in Ouro Preto, Brazil, where he died in 1936.
In their diaries, they described the areas they passed through, discussed Indian tribes they met, and left numerous sketches, photographs, maps, data, and memories regarding the nature and cultures that they had so much enjoyed meeting.