There is a rich tradition of oral history in the balkans that is passed down from generation to generation. Sadly most of it is nationalist propaganda used to inflame hate. In Serb oral tradition Bosniaks are considered as Muslim Serbs and most of the stories involve two friends, one of whom converts to Islam promising to the other he will reconvert when Turks leave but doesnt do so and instead tortures his former friend. Stories of rape and various abuses are also prevalent. All of that was taught to children before the war and long before that, so hate was always there, it just didnt surface until the situation proved favorable to expressing hate. The belief can be summed up the best in a Serb common saying "Poturica gori od Turcina" meaning Turkling is worse than a Turk"

Croat stories are also similar to that the difference being that Bosniaks are considered unenlightened savages who need to be taught to embrace Croat nationality (thus there were far fewer cases of extermination but more cases of forced conversions or name changing when compared to Serb-Bosniak conflict)

So to sum it up there was never harmony, just periods when hate is on the outside and periods when its inside.