Ethnographic Atlas of the Western Russian Governorates and Neighboring Regions

The publication of the atlas coincided with the January Uprising (1863–1864), a period when the question of the national identity of the population in former Poland–Lithuania sharply escalated in the Russian Empire. The Russian government and bureaucratic institutions had an urgent need for statistical data that would prove to both European and domestic audiences that the majority of the region's population was "Russian" rather than Polish.

Roderich von Erckert, a German by origin and an employee of the Imperial Russian Geographical Society, took on the task of classifying the local population. He relied on data from previous studies, including the parish lists of Peter von Köppen.^[3][2] The atlas was published in two versions: in Russian and in French. The French version was specifically intended for a European audience to refute Polish political claims to these territories.

Fragments of the Russian-language (left) and French-language (right) versions of the ethnographic map from the "Ethnographic Atlas of the West Russian Provinces and Neighboring Regions" (1863). The French version differs not only in translation but also in the graphical distortion of the original: Belarusian enclaves are not marked on it (in the Vilnius Region and Podlachia, they were removed entirely; in Western Polesia, the border of the "Little Russians" was shifted so that the enclaves became part of a continuous Belarusian area), although the atlas's tabular data on the number of the Belarusian population in the respective regions remained unchanged.

The primary criterion for determining ethnic identity of Slavs in Erckert's atlas was religious affiliation. The author considered this approach to be "the most correct" and proposed that all Eastern Slavic populations practicing Orthodoxy should be counted as Russians, while all Catholics should be counted as Poles.^[2]

Erckert categorically denied the existence of a "Catholic Belarusian". In his study, he argued:^[4][5][2]

The expression 'Catholic Belarusian' is found, it is true, quite often in scientific articles, but in reality it does not and cannot exist <...>. The commoner calls his language prostaya mova [simple speech], and himself Russian, often even Lithuanian (according to political traditions), or simply a peasant... <...> The Polish nobility, and especially the Catholic clergy, often use the expression 'Lithuanians' about those Catholics whose native language remains Russian. In this case they make a political mistake.

Thus, Erckert combined Great Russians, Belarusians, and Ukrainians ("Little Russians") into a single dominant group of "Russians", contrasting them with Poles and actual Lithuanians, whom he further divided into Lithuanian and Samogitians.^[3]

Despite merging them into a single Slavic tribe, Erckert attempted to identify distinct regional groups of Belarusians within it. In his works, he divided the ethnic territory of Belarusians into three parts and, correspondingly, three groups.

He categorized the first group as "True Belarusians", who inhabited the Vitebsk, Mogilev, the eastern and western parts of Minsk and Smolensk governorates, respectively.^[6]

The second group consisted of the "Black Russians", living in the western part of the Minsk Governorate and the northern part of the Grodno Governorate. However, Erckert noted that the population itself did not use this name, nor did they call themselves Belarusians, and that the local Polish szlachta (nobility) referred to them as Lithuanians.^[7]

The third group—the Podlasians—inhabited the western part of the Grodno Governorate and were considered by the researcher to be the most Polonized segment of the Belarusians.^[8]

Relying on linguistic features, Erckert classified the population of the southern Grodno and Minsk governorates (Western Polesia) as "Ruthenians" (Rusins), perceiving them as a part of the Little Russians (Ukrainians).^[9]