steppes and associated with early Proto-Indo-European, had trade relationship with Old European cultures. Domesticated cattle, sheep and goats, as well as copper, were introduced eastward from the Danube valley around 4700–4500. Copper objects show an artistic influence from Old Europe, and the appearance of sacrificed animals suggest that a new set of rituals emerged following the introduction of herding from the west. The Old European Tripolye culture continued to influence the western part of the steppes, in the Dnieper-Donets region, where the Yamnaya culture was more agricultural and less male-centered. Proto-Indo-European speakers also had indirect contacts with Uruk around 3700–3500 through the North Caucasian Maikop culture, a trade route that introduced the wheeled wagon into the Caspian-Pontic steppes. Wheel-made pottery imported from Mesopotamia were found in the Northern Caucasus, and Maikop chieftain was buried wearing Mesopotamian symbols of power—the lion paired with the bull. The late Khvalynsk and Repin cultures probably traded wool and domesticated horses in exchange, as suggested by the widespread appearance of horses in archeological sites across Transcaucasia after 3300. Socio-cultural interactions with Northwest Caucasians have been proposed, on the ground that the Proto-Indo-European language shows a number of lexical parallels with Proto-Northwest Caucasian. Proto-Indo-European also exhibits lexical loans to or from other Caucasian languages, particularly Proto-Kartvelian. Proto-Indo-European probably also had trade relationships with Proto-Uralic speakers around the Ural Mountains. Words for "sell" and "wash" were borrowed in Proto-Uralic, and words for "price" and "draw, lead" were introduced in the Proto-Finno-Ugric language. James P. Mallory suggested that the expansion of the Uralic languages across the northern forest zone might have been stimulated by organizational changes within Uralic forager societies, resulting partly from interaction with more complex, hierarchical Proto-Indo-European and (later) Indo-Iranian pastoral societies at the steppe/forest-steppe ecological border. Technology From the reconstructable lexicon, it is clear that Proto-Indo-Europeans were familiar with wheeled vehicles—certainly horse-drawn wagons (*weǵʰnos)—as they knew the wheel (*kʷekʷlóm), the axle (*h₂eḱs-), the shaft (*h₂/₃éih₁os), and the yoke (*yugóm). Although wheels were most likely not invented by Proto-Indo-Europeans, the word *kʷekʷlóm is a native derivation of the root ("to turn") rather than a borrowing, suggesting short contacts with the people who introduced the concept to them. The technology used was a solid wheel made of three planks joined together with their outer edges trimmed to a circle. The swift chariot with spoked wheels, which made the mode of transport much more rapid and lighter, appeared