The Caucasus as a bridge of cultures is at the centre of the transfer of innovation between Mesopotamia and Europe in the 4th and early 3rd millennia BC. The 4th millennium BC saw the transfer of knowledge and technical innovations, such as the wheel and the wagon, new metals like silver, copper alloying, the domestication of the horse, and the outbreeding of woolly sheep. All these innovations had far-reaching consequences well into historical times. The contributions contained in this volume, first presented at an international conference, cover the period from the Chalcolithic to the Bronze Age and deal with the geographical area from the Levant to the Pontic steppe and Carpathian Basin.