The cremation cemetery at Miętkie was excavated over several seasons in the early 20th century (Fig. 1). Its first explorer was E. Hollack, who, in 1903−1904, discovered nearly 200 graves, which were subsequently numbered for each individual part of the site (features I.HA.1−22, I.HB.1−161, I.Ha.1−3). The artefacts recovered were sent to the Prussia-Museum in Königsberg. Hollack’s research at the Miętkie cemetery was directly followed by the excavations of two amateur archaeologists, J. Behr and H. Heß von Wichdorff. Their work was not documented, and its only remnants are the collections of finds donated to the archaeological museum in Berlin. Although the artefacts in question were entered into the museum’s inventory as goods from separate burials, the thusly distinguished “grave assemblages” should be treated with great caution. The next excavations at Miętkie took place only in 1912, when F.E. Peiser worked at the site. He recorded 662 features (I.P.1−622), which he described in a field journal together with their coordinates and occasional supplementary schematic drawings. In the same year 1912, Peiser carried out excavations in the southern part of the cemetery, which he designated as “site II” (features II.P.1−77)—no documentation of this research survives. The excavations presented above did not cover the entire area of the cemetery, and further chance discoveries were made at the site in the 1920s, while regular excavations at Miętkie resumed in 2017. Before the Second World War, only a part of the Berlin collection acquired by J. Behr and H. Heß von Wichdorff and drawings of a few artefacts (presented without context) from the much richer material found during the excavations of E. Hollack and F.E. Peiser were published. Due to the almost complete loss of this part of the collection as a result of the war destruction, the main source of knowledge about the cemetery at Miętkie is archival material, mainly museum documentation, with the following records. Under these circumstances, the periodisation of the functioning of the Miętkie cemetery presents considerable difficulties: more than 260 features have not been dated, and most of the others can only be assigned to a very broad chronology, covering either the entire Younger Roman Period or the Late Migration Period. In addition, the datable finds, including artefacts considered to be precise chronological markers, such as brooches or buckles, have a “long circulation period” that exceeds the chronological ranges accepted for the West Balt Cultural Circle. Despite these problems, it was possible to distinguish three major phases of use of the Miętkie cemetery, each lasting about 200 years. Phase I of the use of the Miętkie cemetery is represented by flat graves without stone structures, containing single cremations, often in urns, which are typical of the Bogaczewo Culture. The cemetery at Miętkie was established relatively late, at the end of the Early Roman Period, as indicated by the exclusive presence of relatively late ring-headed pins (Figs. 2:a−f) and pins with a head shaped as a body of revolution, often with a hole or loop (Figs. 2:g−j, 3:b). Among the brooches there were few Early Roman specimens of O. Almgren’s groups II and IV (Figs. 4, 5:h), while brooches with a returned foot, characteristic of the Younger Roman Period, predominated (Figs. 6:b.e.g.h.j.k). The brooches were accompanied by neck rings with wire-wrapped terminals (Figs. 7:b.f, 8:m) and bracelets made of a wide bronze band (Figs. 3:e, 7:c, 8:n), also considered indicative of the Younger Roman Period in the Bogaczewo Culture. The graves with the above mentioned artefacts contained flask-shaped urns of type IB–IE (Figs. 3:a, 6:d, 9:a, 12:a–c) and bowls of type II (Figs. 6:f, 12:d–h), which were usually used as urn lids. Alongside them were vases similar to type IA (Figs. 6:a, 13). Following the chronological systems developed for Central European Barbaricum and Scandinavia, phase I of the cemetery’s use can be synchronised with phases B2/C1−C2, corresponding to the years ca. 150/160−300/310 according to Central European chronology. Phase II is defined by 20 grave assemblages with brooches representing a wide range of the latest forms of Almgren’s group VI: with either a sheet catch (Fig. 14:a.e) or a closed catchplate (Figs. 14:k, 15:a.b). Unique forms of West Balt crossbow brooches with a closed catchplate are the so-called star-footed fibulae (Sternfußfibeln), represented at Miętkie by only one specimen (Fig. 14:p). Other peculiar forms of crossbow brooches with a closed catchplate are iron specimens with a semicircular bow of rectangular cross-section (Fig. 15:l), representing the Praga-Vilkonys type. The pottery that can be attributed to phase II is a good illustration of its ‘transitional’ character, as the best attested group of vessels consists of vases analogous to earlier specimens (Fig. 15:m). The described phase can therefore be defined as a period of transition in phases C3−E1 from the Bogaczewo Culture of the Younger Roman Period (phases C1−C2) to the Olsztyn Group of the developed Late Migration Period (phases E2−E3), which in terms of absolute chronology would correspond to the years ca. 300/310−525/535. Phase III, the final stage of the use of the Miętkie cemetery, can be easily defined as corresponding to the full flowering of the Olsztyn Group, characterised by the presence of numerous plate brooches (Fig. 17:a.f.g). They were accompanied by circular (Fig. 18:a.j), rosette (Fig. 18:b) and cross-shaped (Figs. 17:e, 22:b) disc brooches, crossbow fibulae decorated at the end of the foot with a metope with an oblique cross (Schlusskreuzfibeln; Fig. 18:g.k) and rung brooches (Armbrustsprossenfibeln) representing the full spectrum of their stylistic development (Figs. 18:c, 19:b.c.g.k). In addition, a single pair of late crossbow fibulae with a returned foot and a wide striped bow decorated with incised wire rings and overlays of embossed sheet metal were represented at Miętkie (Fig. 18:d). Ornaments such as binocular pendants of bronze wire (Brillenanhänger; Figs. 17:j, 21:o) and glass “wart” beads (Warzenperlen; Fig. 17:d.k), as well as belt elements, especially buckles with a cross-shaped pin (Kreuzdornschnalle; Figs. 17:c, 18:h, 19:h) and lanceolate strap-ends (Figs. 17:b, 18:j), were also characteristic of phase III. The pottery of phase III is represented by vase-like vessels, sporadically encountered already in phase II but now with characteristic rectangular (Fensterurnen; Fig. 20:a) or circular (Lochurnen; Fig.19:a) openings. Thin-walled beakers with a hollow foot (Figs. 20:b−e, 22:f) are also specific forms, represented by very numerous specimens. The latest finds are brooches in the form of rectangular, flat plates (Fig. 21:d.k.l−n.u), which resemble the so-called Rechteckfibeln of the 6th−10th centuries. A similarly late chronology is indicated by the penannular brooches (Fig. 22:g.h), which resemble specimens dated to the 9th−10th centuries. The brooches in question suggest that the cemetery at Miętkie continued to function until the 8th century, similar to the recently published cemeteries at Stantau on the Sambian Peninsula and at Linkuhnen at the mouth of the Neman River. Due to the long period of use, the rhythm of transformations observed in the Miętkie cemetery can be considered illustrative for the entire Masurian Lakeland, with phases I−III corresponding to the stages of cultural transformation in the area, with the caveat that the formation of the earliest structure typical of the Roman Period—the Bogaczewo Culture—preceded the establishment of the cemetery under discussion. The earliest finds of the Bogaczewo Culture, which are not present in Miętkie, namely pins of types A and B in the classification of B. Beckmann, cuboid quartzite fire-flints, buckles with an extended pin, and pendants in the shape of a spoked wheel, were found at sites in the north-eastern part of the Great Lakes Region and were initially defined as the “Węgorzewo Group” (Angerburger Gruppe). In view of the current state of research, it is more appropriate to treat this group as the “Węgorzewo Phase”, while retaining the name established in the literature, and to include in its inventory highly profiled fibulae of Almgren type 68, eye brooches of the main series of Almgren type 53, and early examples of the Prussian series of Almgren types 57–59. This inventory allows the unit in question to be synchronised with phase B1 and the early stage B2a in the chronological system of Central European Barbaricum and to date it to around the 1st century CE. Such a chronology makes it possible to identify the population of the Bogaczewo Culture with the Galindai tribe mentioned by Ptolemy. The beginning of the second phase of development of the Bogaczewo Culture, for which the name “Mrągowo Phase” has been proposed here, is marked by the appearance of late eye brooches of the Prussian series—Almgren type 61. During this phase, the first specimens of the local form of Almgren type 133 came into use, followed by triple-crest brooches. The co-occurrence of the latter with crossbow brooches with a returned foot of Almgren types 161−162 and 167 indicates that the phase in question lasted until the end of the Younger Roman Period. By this time, the Bogaczewo Culture settlement had spread to the southern part of the Mrągowo Lake District and even further south. One of the new sites was the Miętkie cemetery, which was established relatively late—clearly some time after the beginning of the phase. During the Mrągowo Phase, cemeteries of the Bogaczewo Culture appeared also in the western edge of the Suwałki Region, indicating the penetration of populations from the Masurian Lakeland into the area. A separate issue concerns the ethnic identification of the Bogaczewo Culture population in the Mrągowo Phase: the continued use of the cemeteries established in the Węgorzewo Phase suggests a continuation of the settlement, which in turn, would allow the assumption that the then inhabitants of the Masurian Lakeland were descendants of Ptolemy’s Galindai. However, due to the lack of ancient sources describing this part of Central European Barbaricum in the 2nd and 3rd centuries CE, this identification should be treated only as an untestable hypothesis. In the subsequent Szczytno Phase, the focus of Masurian settlement shifted southwards, resulting in the abandonment of some of the Węgorzewo Phase cemeteries located in the northern edge of the Great Lakes Region. This phase is reflected by stage II of the Miętkie cemetery, which constitutes the longest sequence of graves from a single burial site dating to phases C3−D. However, there are doubts whether these finds can still be attributed to the Bogaczewo Culture. Such a possibility is indicated by the presence of pottery continuing the stylistic motifs of the previous phases; at the same time, the Szczytno Phase is not represented by any endemic form of the Bogaczewo Culture, and all the artefacts that could serve as chronological markers were either interregional forms, Sambian imports or, at best, imitations of Sambian designs, as exemplified by the star-footed brooches and wide, tongue-shaped strap-ends with stamp decoration. Therefore, this situation can be seen as an indication that the Masurian Lakeland in the Szczytno Phase was a periphery of the Dollkeim/Kovrovo Culture, distinguished from its central areas by the continued presence of local pottery. The Miętkie cemetery provides yet another argument for extending the duration of the Bogaczewo Culture: the horizontal stratigraphy of the site indicates the distribution of burials from all three phases over its entire area (Fig. 23). The cemetery functioned according to the rules adopted in the Younger Roman Period, the only change being the aforementioned impoverishment of the grave furnishing—a phenomenon observed throughout Central European Barbaricum. All these observations point to an undisturbed, continuous use of the cemetery. The prolongation of the Bogaczewo Culture until the end of phase D suggests identification of its population with successive generations descended from Ptolemy’s Galindai. As in the case of the Mrągowo Phase, such an interpretation should be considered an attractive but unverifiable hypothesis. In the Late Migration Period, the Olsztyn Group, the name of which is used here to designate a phase, occupied the area between the Upper Łyna River and Lake Śniardwy—in the centre of its territory was the cemetery of Miętkie, whose phase III is dated to phases E2−E3 and is characterised by the presence of plate brooches, window urns, footed beakers, buckles with a cross-shaped pin, lanceolate strap-ends and plaques with openwork decoration. These finds allow the cemetery of Miętkie to be considered a typical site of the Olsztyn Group. In this situation, its uninterrupted use, together with the presence of elements reflecting the traditions the Bogaczewo Culture—especially pottery, some forms of which, such as vase-like vessels, were found in assemblages confidently dated to phase II—becomes more significant. This continuity suggests that the formation of the Olsztyn Group—despite attempts to consider it either as the result of the arrival of an alien, Germanic population or the return of a group of Galindai who had previously wandering to southern Europe with the Goths—was the manifestation of a local evolution of the cultural model of the Balt population, most likely belonging to the Aestii tribe mentioned by Jordanes.