This rethinking of basic Byzantine issues is vastly based on the re-interpretations and new commenting of the classic text of ‘De Administrando Imperio’. This is especially clearly seen, since this publication takes place against the backdrop of a fundamental rethinking in modern Byzantine studies of political history and the system of power organization in the ‘Eastern Roman Empire’ of the 10th century. It is shown that his commentaries accompanying this translation are extremely primitive, the author doesn’t follow scientific methods and he isn’t familiar with modern scientific literature. The article is a critical essay about an attempt to translate the Constantine Porphyrogenitus’ treatise ‘De Administrando Imperio’ into an artificially archaic «Pseudo-Slavic» language, made by R.A. Gimadeev. On the other hand, it aims to provide a thorough historical analysis and offer a possible interpretation in opposition to the view, still largely extant in the Croatian scholarship, that this account is an evidence for an early presence of the group called Croats in southern Pannonia. On the one hand, it seeks to detect the methods or strategies used by the royal compiler in trying to elucidate the past. Taking a different approach from the complete dismissal of the two sentences as a pure fiction or a mere literary device, the paper instead attempts to trace the concept behind this account as well as its underlying meaning. And they also had an independent ruler who was sending envoys, though only to the ruler of Croatia from friendship. The paper endeavours to discuss anew a scholarly puzzle related to the Croatian early Middle Ages and centred on a few lines from Constantine VII Porphyrogennetos's De administrando imperio, which in English translation are as follows: And of the Croats who arrived to Dalmatia one part separated and ruled Illyricum and Pannonia.