Wheeled vehicles – wagons or carts which are supported and moved around by round wheels – had a profound effect on human economy and society. As a way to efficiently carry goods for long distances, wheeled vehicles allow for the broadening of trade networks. Communities can expand, if there is no need to live close to food production areas. With access to a wider market, craftspeople can more easily specialize: you could argue that wheeled vehicles facilitated the use of traveling markets. Not all changes are good: with the wheel, imperialists could expand their range of control, and wars could be waged farther afield.
It's not simply wheels alone that drives these changes. Wheels in combination with the domestication of suitable draft animals such as horses and oxen lead to the construction of roadways. Roadways predate wheels by a couple thousand years, as does the domestication of cattle. Wheels were invented in the Americas, but because draft animals were not available, wheeled vehicles were not. Trade flourished in the Americas, as did craft specialization, wars, and the expansion of settlements, all without the wheel: but there's no doubt that having the wheel did drive many social and economic changes in Europe and Asia.
Wheeled vehicles spread across Europe by the third millennium, and clay models of high sided four wheeled carts are from found throughout the Danube and Hungarian plains, such as that from the site of Szigetszentmarton in Hungary.
The earliest evidence for wheeled vehicles appears simultaneously in Southwest Asia and northern Europe, about 3500 BC. In Mesopotamia, pictographs representing four wheeled wagons have been found on clay tablets dated to the late Uruk period. Models of solid wheels, carved from limestone or modeled in clay, have been found in Syria and Turkey, at sites dated approximately a century or two later. Although long-standing tradition credits the southern Mesopotamian civilization with invention of wheeled vehicles, today scholars are less certain, as there appears to be a nearly simultaneous record of use throughout the Mediterranean basin.
In technological terms, the earliest wheeled vehicles appear to been four-wheeled, as determined from models identified at Uruk (Iraq) and Bronocice (Poland). A two-wheeled cart is illustrated at the end of the fourth millennium BC, at Lohne-Engelshecke, Germany (~3402-2800 cal BC [cal BC]). The earliest wheels were single piece discs, with a cross-section roughly approximating the spindle whorl: that is, thicker in the middle and thinning to the edges. In Switzerland and Southwestern Germany, the wheels were fixed to a rotating axle through a square mortise. Elsewhere in Europe and the Near East, wheels were attached to a fixed, straight axle.
Wheel Ruts and Pictographs
In Europe, parallel wheel ruts have been identified from beneath him megalithic long barrow at Flintbek. The oldest known evidence of wheeled vehicles in Europe comes from the Flintbek site, a Funnel Beaker culture near Kiel, Germany, dated to 3420-3385 cal BC. A series of cart tracks was identified beneath the northwestern half of the long barrow, measuring just over 20 m long and consisting of two parallel bundles of wheel ruts, up to 60 cm wide. Each single wheel rut was 5-6 cm wide, and the gauge of the wagons has been estimated at 1.1 to 1.2 m wide.
At Bronocice in Poland, a Funnel Beaker site located 45 kilometers (28 miles) northeast of Kraków, a ceramic vessel contains several, repeated pictographs of a schematic picture of a four-wheel wagon and yoke, as part of the design. The beaker is associated with cattle bone dated to 3631–3380 cal BC. Other pictographs are known from Switzerland, Germany and Italy; two wagon pictographs are also known from the Eanna precinct, level 4A at Uruk, dated to 2815+/-85 BC (4765+85 BP [5520 Cal BP]), a third is from Tell Uqair: both these sites are in what is today Iraq. Reliable dates indicate that two- and four-wheeled vehicles were known from the mid-fourth millennium BC throughout most of Europe. single wheels made of wood have been identified from Denmark and Slovenia.