The author studies the Old and Middle Hungarian toponymic corpus of Ugocsa, the northeastern county in historical Hungary. The corpus on which the work is based consists of nearly 2,000 data. The primary goal of the research is to prove that the linguistic features of the toponyms of the county refer to the presence of ethnicities and their historical characteristics. The author pays great attention to the origins and subsequent relations in Slavic-Hungarian language contact as reflected by toponymic corpus. He also examines ethnicities that are generally regarded as of minor significance. Another aim of the research is to display the evolution of the toponymicon and seek answers to the following questions: can toponymic-type-specific features of some pronounced tendencies be identified in the formation and transformiation of the onomastic corpus? Does the analysis of a large-scale (onomastic) corpus give an opportunity to specify our current knowledge? Does it confirm the results of other disciplines?

In the first chapter, the author describes the changes in the physical geography of Ugocsa that could have taken place around the time of and following the Hungarian Conquest of the Carpathian Basin. In the second chapter he evaluates and summarizes the results of other disciplines (history, archeology, linguistics) with regard to the past of the county past. In the third chapter, with a view to linguistic strata, he analyzes the Old and Middle Hungarian toponymic system of Ugocsa, and divides the corpus into three types of toponyms to reach more reliable results, which are river names, settlement names and microtoponyms. In the analysis, he describes Hungarian and borrowed toponyms in an integrated system. For instance, the Old Hungarian hydronyms Beberke (< Slavic bebrъ ~ bobrъ ‘beaver’) and Hódos (< Hung. hód ‘beaver’) were formed from the same animal name, but the first one is part of the Slavic stratum, whereas the second is of Hungarian origin. The fourth chapter is devoted to the discussion of methodological principles of name giving and extrapolation. Then the author proceeds to demonstrate Old and Middle Hungarian onomato-systematical correlations of the county. It can be inferred from the research that hydronyms in form a dominant group of toponyms in nearly the whole of the era, which adds to the general significance of microtoponyms. In the last chapter, the author sums up the experience gained during the research.