The article presents new radiocarbon determinations obtained for collective graves from the Trzciniec cultural circle (TCC) in Central Poland. The dated graves were associated with the Konstantynów group and belong to the late phase of the TCC. As a result of the research carried out on this form of burial, it was possible to distinguish two types of graves and locate their concentrations in Central Poland in the zone where the materials of the Konstantynów group occur. The established dates, together with the technological and stylistic analysis of ceramic materials, make it possible to determine two time horizons in the late phase of the Trzciniec culture circle.

The subject of this study will be the discussion and comparison of material remains together with the radiocarbon dates obtained from three collective graves of the Trzciniec cultural circle (TCC) from Central Poland. We are not going to discuss here the subject of the genesis of cremation in TCC, which has been undertaken recently by J. Górski, P. Makarowicz and A. Wawrusiewicz (2017). The aim of the research is an attempt to arrange chronologically this phenomenon in the course of the TCC phases in Central Poland in the light of the C14 dates obtained. It should be noted that cremation burials occur in the TCC throughout its territorial range for a longer part of development of this cultural circle (P. Makarowicz 2010, 244). With reference to Central Poland, there are several types of such burials i.e., registered as urn graves, e.g. at the cemeteries in Błonie, site 1, Łęczyca district and Stobnica-Trzymorgi, the site 3, Piotrków district as well as in the urnless form (so-called single pit burials), e.g. in: Gledzianówka, site 3, Stobnica-Trzymorgi, site 1, Piotrków district, Godziesze Małe, Byszewy, site 3, and collective burials in Polesie, site 1, Łowicz district, Teofilki, site 1, Łęczyca district, Borek, site 1, Kalisz district, Konstantynów Łódzki, site 3, Pabianice district, Krokorczyce, site 1, Łęczyca district, Gorzew, site 4, Sierpów, site 1, Zgierz district, Smardzew, site 15, Sieradz district and Szewce Owsiane, site 9, Kutno district. Urnless cremation burials seem to occur on the basis of their arrangement in the cemetery space in two forms. They were most likely under hypothetical burial mounds, which may be indicated by the distances they were located in relation to each other, as well as burials without mounds. With reference to the urnless collective burials occurring in the area of Central Poland (Fig. 3), there are two basic types of burials, excluding burials in the form of the so-called burnt houses of the dead. Type 1 – these are constructions containing structures in the form of a stone kerb and paving. Type 2 – no stone structures have been reported in cemeteries. Most of the sites known in the literature were discovered by accident in the 1930s and 1940s, while excavating sand or gravel. At this stage of the discoveries there were only two cases where these finds were researched in the course of excavations, and this applies to the sites in Kębliny and Krokorczyce. Several sites are the latest discoveries already made in the 21st century in the course of systematic research, for example Polesie, site 1, Smardzew, site 15, Teofilek, site 1, Gorzewo, site 4 and Szewce Owsiane, site 9. Individual finds have been presented in scientific literature several times, but never in its full scope, mainly considering the presentation of grave inventories uncovered at the cemeteries. All the presented complexes are part of the transition / Konstantynów group distinguished by K. Jażdżewski, while A. Gardawski in his work from 1959 called this phenomenon a “transition phase” from the Trzciniec culture to the Lusatian culture, which led to name this stage the Łódź phase. Even then, the authors distinguished its two phases, the older one with rectangular pits and stone structures, mostly for several individuals, and the younger one with round pits and intensely burned bones, as urn and urnless graves. Below there are three burial complexes from Central Poland for which radiocarbon determinations were obtained (Fig. 1). It was possible thanks to the grant from the University of Rzeszów entitled “Dating late phases of the Trzciniec culture in Central Poland” – project no. IA-13/2014/508. Therefore, let us present selected burial complexes. Kębliny, Zgierz district, site 1–3, grave 2. The site was examined by W. Kasiński in the years 1935–36. Based on the archival records and the review of the preserved materials, the site should be considered a multicultural site, including materials from the late Neolithic to the Bronze Age. The grave inventory consisted of several vessels preserved in fragments. Among them, there are vases and amphorae with a uniform decorating style in the form of vertical fluting covering the entire body, sometimes in combination with horizontal fluting. Konstantynów Łódzki, site 3, grave 1. The site was discovered in 1946 by K. Jażdżewski, who, found pottery sherds and burned bones in the sand sediments during field research and then decided to explore the grave. Thus, one burial was discovered with a stone structure in a rectangle shape with dimensions of 350×100 cm, with human bones and pottery sherds. The inventory included 12 reconstructed vessels and several fragments from the others. Krokorczyce, site 1, Zgierz district, grave 1. The site was discovered in 1947 during field research, when an outline of a pit with bones was recorded in the profile of a gravel pit. It was the only site where rescue excavations were carried out to protect the gravel slope. In the course of work, 5 graves were uncovered, including three ones with stone structures in the form of a rectangular cist, creating collective graves, and two single graves. The spatial arrangement of large collective graves may suggest the presence of earth mounds above them. Only two burials (1 and 5) were furnished. The inventories included vessels decorated with vertical fluting and one plain item and a bronze bracelet. The analysis of the inventories of graves discovered at the aforementioned three sites shows that all these complexes were furnished with vessels decorated with vertical or slightly oblique fluting located on the entire surface of the body, from the neck to the base. Such ornamentation of the vessels is dominant in the burial from Kębliny and Krokorczyce, while in Konstantynów Łódzki it was found only on three out of several vessels, where forms without any ornaments predominated. Speaking of the forms of vessels for the graves in Kębliny and Krokorczyce, vases / amphorae and bowls were distinguished, whereas referring to the burial uncovered in Konstantynów Łódzki, pots with plain surfaces and one with a rough surface were distinguished, as well as cups and a bowl were record. Taking into account the micromorphology of the vessels, the edges of the rims are not thickened or thinned, while the bases have a basic form without defined or slightly defined shapes. On the other hand, when analysing the technology, it is possible to distinguish two technological groups, differing in the granulometry of the used admixture in the form of stone grit and sand. The first group are vessels where an admixture was coarse, medium and a small amount of finely grained stones, whereas the second group included the forms made of a clay paste thinned with fine stone grains and sand with a small share of medium stone grains. Apart from the ceramic forms coming from the discussed graves, only the burial from Krokorczyce provided one bronze bracelet with an oval crosssection and narrowing endings, decorated with oblique incisions, which should be attributed to type B bracelets according to E. Kłosińska. With regard to the three discussed cemeteries, four radiocarbon determinations were established, two for the burial from Konstantynów Łódzki and one for the burial 2 from Kębliny and one for the burial 1 from Krokorczyce. All dates were obtained from burnt bone remains from the carbonate fraction. Radiocarbon determinations were made in 2015 as part of the above-mentioned grant, at the Poznań Radiocarbon Laboratory by prof. T. Goslar and in the studio of prof. M. Krąpiec (table 1, fig. 8). Considering the grave from Kębliny, the obtained result indicates the date 3030 ± 30 BP, which provides (with an error of 68.2%) the range of the years 1374–1226 BC, while with the error of 94.5%, the time range is 1396–1135 BC. Furthermore, for Konstantynów Łódzki, the result was 2975 ± 35 BP, for which (with an error of 68.2%) we get the range of 1259–1128 BC, and in the case of an error of 94.5%, we get the range of 1369– 1056 BC. Moreover, regarding the burial 1 from Krokorczyce, the result was 3285 ± 35 BP, which (with an error of 68.2%) gives the range of 1612–1527 BC, and with a range of 94.5%, the result covers the years 1644–1460 BC. The result obtained in the laboratory in Skała by prof. M. Krąpiec for the grave in Konstantynów Łódzki was avoided due to too high error compared to the other three determinations. The stylistic materials found in the discussed graves correspond to the stylistic group GS4 in Polesie 1, which appeared already in the 13th and 12th centuries BC, and the oldest vessels decorated with fluting might have existed since the 14th century BC. On the other hand, at the site in Szczepidło, the separate ornamental groups XVI, XVII and XVIII are dated, respectively, with an error of 68.2% in the range of years: 1281–1266 BC, 1297–1280 BC and 1293–1276 BC (P. Makarowicz 2017, Fig. 132, 133, 136). Such determinations give the range 1297–1266 BC with an error of 94.5%, and 1301–1256 BC with an error of 68.2%, i.e. generally covering the 13th century BC and it fits BrC and BrD (III Bronze Age Period). Unfortunately, the problem is caused by the results obtained for the grave in Krokorczyce, which determine the period between 1612–1527 BC. Such results differ significantly from the dating of complexes containing materials decorated with different types of fluting, both in Polesie and Szczepidło. Summarizing the three discussed complexes, they can be considered as representatives of two stages of the late phase of the Trzciniec culture, as evidenced by the participation of vessels decorated with vertical fluting and plain vessels. Thus, the graves from Kębliny and Krokorczyce represent the older stage of the late stage of the Trzciniec culture, while Konstantynów Łódzki should be placed in the younger stage, preceding the appearance of the so-called cultural circle of the Lusatian urn fields, which takes place in Central Poland in HaA1, i.e. in the second half of the III Bronze Age Period.