The opera Ambrož and Katarina was written by composer Gregor Zagorc, conductor of the Dobreč Tamburitza Orchestra. He got the idea in 2015 when his orchestra first started playing opera music. They discovered that tamburitzas worked very well as an accompaniment to opera singing and that the two complemented each other wonderfully. Composer Zagorc then started toying with the idea of composing a tamburitza opera. He learned that no such opera had ever been written, all being only transcriptions, adaptations of existing works composed for the symphonic orchestra, which made him even more motivated to take on the project of writing the world's first tamburitza opera.

He also wanted to find a good libretto and incorporate Bela krajina in the narrative so that people in Slovenia and abroad could get to know the region better. Writer and musicologist Nina Novak Oiseau took up the challenge of writing the text. The libretto and opera are based on historical facts, as between 1660 and 1850 the castle in which the story is set was home to the Gusič family. The author found inspiration in a local legend, which formed the basis for the story's dramatisation and literalisation. "The language is rich and very archaic at times. It's the first opera based on the folk traditions of Bela krajina. It could also be called an ethno-opera," said the author of the libretto, Nina Novak Oiseau.

In writing the opera that includes all the traditional characteristics, composer Zagorc focused on ethno-music from Bela krajina and the harmonies of the late Romantic period In addition to tamburitzas, he also incorporated the woodwind and percussion sections, which, he said, certain parts of the orchestral piece needed for dramatic effect.