Their owners waged a bloody inter-ethnic war but when it comes to the sport of giant bull fighting and especially its grandest event, the Corrida of Cevljanovici, there are "no nationalities" in Bosnia.
Fourteen beasts with carefully polished horns, have been hand-picked to compete in the "Champions League" of the summer corridas.
They will draw a huge crowd of Bosnians, Serbs and Croats, a rare meeting place for all three communities who fought against each other between 1992 and 1995.
"There are no ethnic divisions here," said Ivo Ilic, a Bosnian Croat who has brought his bull Lozonja to fight. "We are all like siblings."
It is played out annually on a huge natural plateau, some 1,000 metres (3,300 feet) above sea level, some 40 kilometres (24 miles) north of Sarajevo.
The event took place in mid-August and even the almost unbearable heat -- temperatures broke 39 degrees celsius (102 farenheit) -- did not prevent thousands of people of all ages coming to the valley, where the air is filled with the smoke of numerous barbeques as skewers slowly rotate lambs from the early morning onwards.
In dozens of tents turned into makeshift restaurants, a kilo of freshly roasted lamb cost about 10 euros ($13), not a cheap treat in a country where the average monthly salary is just 400 euros.
Numerous brass bands play local folk music as scantily dressed young women dance on the tables in the tents and delighted drinkers watch.
Outside, hundreds of men and women dance the traditional "kolo" in a circle, hand in hand, as some of them did decades ago in the former communist Yugoslavia.
"The corrida of Cevljanovici is like a melting pot with all ingredients, Serbs, Croats and Muslims," said Besim Gljiva, one of its organisers.
Gljiva said bull fights in Cevljanovici have a 66-year-long tradition, but various festivities were organised here as far back as the 19th century.
There was a break in bull fighting during the war but once the conflict -- which left some 100,000 dead -- was over, the festivals started again.
-- No blood, no matadors --
Bull breeders from all three communities came together to form a national federation in 2003 and at least 1,000 bulls take part in fights organised every Sunday during the summer throughout Bosnia.
Victory at Cevljanovici could enormously increase a bull's value, up to 25,000 euros, although there is no prize money for the winner.
The winning bulls are treated by owners almost as family members; when they die, some even organise funerals for the glorified animals.
But this is not a Spanish-type corrida: there is neither blood nor a matador.
The bull-on-bull fights never end in death as it is banned to sharpen their horns, to prevent any serious injury.
The fight ends when one of the powerful animals flees the arena, surrounded with a two-metre (six-foot-seven-inch) wire fence, thus admitting the superiority of its rival.
Some battles end without any contact between the two bulls, while others last for several minutes as the rivals push each other's heads.
Stevo Mumovic, a Serb from the eastern town of Han Pijesak, is a proud owner of a bull that has never lost a fight.
But this time, he was here to congratulate his Muslim friend Nezir Saracevic, whose bull Garonja, the strongest at the tournament, weighing 1,200 kilos (2,650 pounds), had just won a fight.
"It is a special glory to have the strongest bull. This is the biggest corrida, the most visited, by people from all communities," Saracevic said proudly.
Those wishing to congratulate him, however, cautiously avoid any sudden move, afraid to upset a huge black beast seemingly guarding his owner.
"He is like a mountain!" a man shouts, pointing at the bull, now resting after chasing his rival out of the arena through a fenced corridor.
Owners of defeated bulls are, however, quick to join the winners at a table covered with cold pints of beer.
Bosnian Croat Renata Prenjkovic, the only woman among the bull breeders, enjoyed victory against a fellow Croat's bull.
"This is a sport without nationality. As we all know each other, we are friends. But I am especially happy today because I beat Ivo, a Croat," Prenjkovic laughed.