In the paper, on the basis of several dozen examples of hydronyms from eastern and north-eastern Mazovia, the erroneous attribution of written sources and, as a consequence, their incorrect identification and location were shown. These kinds of mistakes can be found in toponymical, hydrographical and historical publications. It is the result of taking attestations from the context of the source, poor knowledge of the history and the geography of the studied area, as well as the poor knowledge of Latin and the lack of verification of hypotheses found in older literature.

There are more than 350 fl owing waters in Poland with names containing a colour adjective. Etymological propositions mention sometimes various physical attributes such as the colour of the water or of the bottom, or even a possible symbolical usage connected e.g. with the cardinal directions, but most often they limit themselves to citing the literary version of the adjective, and there end their inquiry. The goal of the present paper is to establish to what degree physical attributes can explain the use of colour epithets; and if they cannot, then whether there is any reason to believe that there existed in the past a more elaborate system of colour symbolism.

The hydronym Szywra refers to the small river in the Warta basin flowing in the central part of Greater Poland. Although its name remained unclear for most of the researchers, it was believed to be of Pre-Slavic or Balto-Slavic origin. The paper reveals that these hypotheses were based on the wrong interpretation of the source material, and provides a new etymology for the name Szywra. Based on the critical analysis of all of the reachable records of names referring to the river Szywra, it has been proven that its Polish name is an adaptation of the former German name Schieferbach. Such a process was possible due to the long-term bilingual situation in the region of Greater Poland.

Geographical names are extremely helpful in giving evidence of early settlements and their inhabitants due to their solid anchorage in the landscape, even in the case of population changes. Through the investigation of these place names, information can be gathered not only on the name giver, but also on the settlers who took on the names later on. Therefore, it is considered that any linguistic investigation has to start from the river and place names of a region.

The utilization of geographical names yields the following findings:

— The centre of Old Slavic names is situated on the northern slope of the Carpathian Mountains, approximately between Bukovina and Krakow; it is based on a substrate of older, Indo-European hydronyms.

— The expansion of the East Slavic tribes bypasses the Pripyat Marshes and extends further through Central Russia and especially to the North and the East.

— West Slavic settlers reach their new settlement areas through migration from Bohemia and further on to Saxonia and Thuringia, and also through Western Poland to Brandenburg and Mecklenburg-Western Pomerania.

— The migration of the South Slavs takes place in two big, yet separate flows, on the one hand through the Moravian Gate to Slovenia, Hungary and Croatia, and on the other hand on the Eastern edge of the Carpathian Mountains to Serbia and Bulgaria.