In a sense, this study has been in the “making” since my first field experiences in southeastern Iran in the late 1960s; ideas first germinated decades ago as a graduate student have taken a long time to mature. The conception and initial writing of this narrative began in fall 1999 when I was completing a Humboldt Fellowship at the Eurasien Abteilung, DAI, in Berlin under the sponsorship of H. Parzinger, then Direktor of this division of the German institute. My stay in Berlin was sandwiched in between participation in two international conferences that were seminal for the formulation of many of the ideas in this account. In late August 1999 I had the good fortune of participating in an international conference at Arkaim in the southern Urals, which was organized by G. B. Zdanovich and which now has been published as Complex Societies of Central Eurasia from the 3rd to the 1st Millennium BC: Regional Specifics in Light of Global Models (Jones-Bley and Zdanovich 2002). A few months later, in January 2000, I attended a conference held at Cambridge University entitled Late Prehistoric Exploitation of the Eurasian Steppe, which was also the title of a book previously published by the McDonald Institute for Archaeological Research (Levine, Rassamakin, Kislenko, and Tatarintseva 1999). The papers from this conference were published subsequently in two volumes, both of which are extensively cited in this study: Ancient Interactions: East and West in Eurasia (Boyle, Renfrew, and Levine 2002); and Prehistoric Steppe Adaptation and the Horse (Levine, Renfrew, and Boyle 2003).