The 3rd millennium BC is represented in the Caucasus by good precipitation and warm temperatures, which promoted a good forest cover in the Bedeni Plateau and the Trialeti region. This probably influenced the dramatic transformation in human behaviour and material culture in the region, represented by the appearance of the so-called Early Kurgan period by the mid–3rd millennium (Karim, Sepideh, and Mohammadi 2018).
This process has been associated with newcomers of a significantly different lifestyle and means of subsistence, possibly associated with a mobile economy, appearing at the same time as the Kura–Araxes traditions disappear. This evidence and the lack of proof of coexistence with the new population suggest a violent end of the culture in the region. In this push–pull process, Near Eastern societies form the south had an important role, judging by the cultural changes of Kura–Araxes communities, and the adoption of a sedentary village life by the newcomers (Karim, Sepideh, and Mohammadi 2018).
The appearance of fortifications in certain sites before the end also evidence the increase of intergroup conflicts and militarism during the Early Bronze Age. While the new groups of cattle herding pastoralists with wheeled carts and oxen-pulled wagons appear in the north, the Kura–Araxes communities subsequently moved farther south. It is unclear if the newcomers are part of a southern Caucasus culture – associated with the emerging Trialeti culture –, or if they came from further north, but some settlements seem to have been abandoned without traces of a violent end (Karim, Sepideh, and Mohammadi 2018).
Although the appearance of barrow cultures is abrupt, a transitional period can be observed in certain sites, showing late Kura–Araxes and local elements at the same time. Communities of the Middle Bronze Age I (Martkopi, Early Trialeti) buried their dead beneath large stone mounds, circular in plan, sometimes covered with a layer of earth, and their dimensions likely reflected social status. The most common item in funerary assemblages is pottery. Graves are often multiple (Karim, Sepideh, and Mohammadi 2018).
The Bedeni barrow tradition (in the high country and the lowlands) shows a more diverse range of burials, with the most popular one represented by large timber structures constructed in a deep rectangular or square grave pit, with aboveground mortuary architecture. Barrows show occasionally a gender-based differentiation reminiscent of the Yamna culture, and sometimes wagons are included in the graves, as was typical of some north Pontic groups. Not all burials were monumental or had a rich assemblage (Karim, Sepideh, and Mohammadi 2018).
The few studied Bedeni settlements show villages surrounded by defensive structures—e.g. a stone perimeter wall, or flanking ditches—formed by multiple houses with a plan reminiscent of the Kura–Araxes tradition: square with slightly rounded corners, with an anteroom and a main rectangular room with a central fixed, baked-clay hearth. Innovations in ritual behaviour with respect to the previous period is the appearance of platforms, which apparently replace hearths as focal points; the use of pit digging and filling; and also the burning of abandoned villages (Karim, Sepideh, and Mohammadi 2018).
Bedeni pottery shows coarse wares proper of the previous Kura–Araxes period, but also an innovative and highly developed potting tradition inspired over time by new advances in metalworking, since many vessels have a metallic look about them. There is a high level of woodworking, and sophisticated lithic industry, with a new projectile design different to the tanged and barbed arrowheads of the Kura–Araxes, more effective with grater penetrating power (Karim, Sepideh, and Mohammadi 2018).
In the North Caucasus steppes and piedmont, continuity with Steppe ancestry is seen. In the Caucasus region proper and to the south, the latest Kura–Araxes samples available and the subsequent North Caucasus, Dolmen, and Lola samples depict continuity of a typical Caucasus ancestry (see §v.2. Early Caucasians), hence the described prehistoric geographical and genetic barrier to steppe invasions (Wang et al. 2019).
Increased CHG ancestry (ca. 60%) is also found among three Early Bronze Age individuals from the Kura–Araxes culture in Armenia dated ca. 3300–2500 BC (Lazaridis et al. 2016), with a late sample (ca. 2550 BC) showing what seems to be a resurge of haplogroup R1b1a-L388 (formed ca. 15100 BC, TMRCA 13600 BC), ancestral to R1b1a1-P297, in the area, with subclade R1b1a2-V1636 (formed ca. 13600 BC, TMRCA ca. 4700 BC).
An outlier from Hajji Firuz Tepe in the north-western Zagros Mountains harbours elevated Steppe-related ancestry and clusters closely to a Yamna outlier from Ozera, Ukraine, and even more closely to Maikop and Armenia Chalcolithic samples (Narasimhan et al. 2018). This is consistent with the incorporation of groups similar to the known Maikop outliers of the northern Caucasus within the expanding Kura–Araxes groups (see §vi.4. Northern Caucasians), receiving thus contributions of Maikop and/or Kura–Araxes from the south.
Even though the radiocarbon dates published for the site (in this case ca. 2465–2286 BC) are unreliable, because of the collapse of different archaeological layers, it represents in any case most likely a Caucasus population with Steppe ancestry, rather than a direct migration from the steppe. The invasion of a Maikop-related population to the south is compatible with the described presence of wagons and rich assemblages in Bedeni. Given the uncertain dates, a late steppe-related population cannot be discarded, although Iron Age steppe-related populations, probably incoming from the Balkans, show a more southern cluster in the PCA (see §viii.14. Caucasians and Armenians).