My dissertation examines the transformations in the regulation of illicit trade and economic crime across the eastern Mongolian portion of the Russian-Chinese border from the period of 1860 to 1921, during which both were a persistent and widespread concern for the Qing and Russian empires. Although no studies on contraband between these states exist, preliminary research has demonstrated that illicit trades ranged from counterfeiting and illegal money lending to the smuggling of weapons and bio-resources. Disputes over trade and natural resource use forced the various administrations along the frontier – Chinese, Russian, and the semi-autonomous Khalkh-Mongolian and Buryat-Mongolian administrations – into contact with one another, as each negotiated competing conceptions of market regulation. What ensued was the intersection of not only multiple legal regimes, but also of quantitative regimes – the numerical calculation of resources, production, and taxation. Preliminary research has led me to approach regulations in Mongolia as an ecology of economic theories and practices, which converged at key points to produce knowledge about Mongolian trade that was both specifically economic and quantifiable. Therefore, rather than asking how the abstract entities of “state” and “economy” interacted, I examine how the development of new quantitative methods themselves transformed both Russian and Chinese economic practice. The National Archive of the Republic of Buryatia in Russia, to which I have conducted two research trips, contains a wealth of hitherto relevant and unexamined sources. Although economic historians have produced numerous studies of Chinese and Russian economic growth and decline, mine will be the first to explore the relationship between efforts to manage the economy and to make it legible through quantification. By examining this process in a borderland, my project also sheds light on the interconnected histories of economic modernity in Russia and China.