The aim of the article is to address the question of the identity and whereabouts of the Croats who are known to have lived in the Western part of Slav Europe in the early Middle Ages. The introduction lists three highly dubious, though not uncommon practices, which have adversely affected the state of research into the Northern Croatia. The first of them con-sists in arbitrary assessments of the relative significance of individual sources which may lead to selective use of data to construct far-reaching hypotheses while misinterpreting all the remain-ing evidence. Another grave danger lies in sticking to a schematic and anachronistic view of early Slavic societies, while failing to take due account of their complex and volatile ethnopolitical structures. Finally, the third danger is connected with the ambition to put on the table every-thing that can be found in a source, no matter how relevant and how little it may be worth. Key cases of the confusion caused by such flawed research practices are discussed in the analytical part of the article, which is principally dedicated to a review of the various conjectures about the home of the Northern Croats. A thorough analysis of the well-known 1086 description of the boundaries of the Bishopric of Prague (DH IV 390), the chorographic work of Alfred the Great and some other sources strongly suggest that the Croats may have been present in Upper Silesia in the 9"'-10th century. This conclusion is not inconsistent with the presence in that region of Golfszyce, Opolanie and maybe Lupiglaa, provided that those tribes were of Croatian descent. A similar point was made by Czech scholars, yet the author of this article finds their extension of the Croatian homeland to Lower Silesia unwarranted. Assuming that the Croats indeed lived in Upper Silesia, he finds no difficulty admitting that they may well have extended on Bohemia. Taking his cue from Constantine VII Porphyrogenitus's De administrando imperio he goes on to suggest that the name "Croat" may have been applied to the tribe of Czechs sensu stricto, even though this conjecture cannot be verified in other sources. While the claim that the Croats lived in Malopolska or on the Dnester is found to be based on most implausible evidence, the referenc-es to their stay in Bohemia or Russia do carry some weight. In the next stage of his investigations the author examines a contemporary Arab Book of Travels and the Byzantine De administrando imperio, two sources where the name Croat is re-peatedly applied to two major West Slavic political powers, 9th-century Moravia and 10th-century Bohemia. Both writers point to the extraordinary role played by the Northern Croatian ethnos in West Slavic Europe; a fact which is corroborated by the numerous traces it has left in local place-names and the supremacy of the designation Croat over all other tribal names in Upper Silesia. This prompts the suggestion that the high respect that the Croat ethnonym enjoyed in Bohemia and Moravia may have reflected a period of domination of tribes believed to be Croat while the use of ethnic or geographical toponymy with Croatian associations may have been connected with myths of South Croatian descent. However, a less speculative interpretation of all those tantalizing pieces of evidence will only be made a posteriori, ie. once a comprehensive, coherent vision of the early medieval societies, their structures and transformations has been put in place. The article sees in the creation of such a model vision the first indispensable step towards the solution of the old mystery of the White Croats. Another mystery waiting for a solution is the related problem of ethnic Croatian toponyms which are scattered all over Slavic Europe, ie. get-ting an insight into their dating and the manner in which they came to be adopted in the far-flung regions of Central and Eastern Europe.