America’s peculiar preoccupation with the U.S.-Mexico border as a site for national security threat draws on a deep well of historical precedent, including the strange story of “prayer rugs in the desert.” Though contemporary discourse frames the question of border security around the restriction of irregular immigration by Latin Americans, America’s first attempts at border control targeted Asian and Middle Eastern migrants. This paper examines the development of U.S. federal policies to prohibit and police cross-border mobility of Turkish, Syrian, and Assyrian migrants coming from Mexico, from the Mexican Revolution to the Great Depression. It argues officials targeted Middle Eastern migration specifically on Islamophobic bases, transforming Muslim mobility into a perceived national security threat. By extension, U.S. experiences of combatting irregular border crossings by Middle Eastern migrants shaped America’s first border control policies, imbuing border agencies with institutional perceptions of crossings as culturally threating that later carried over to policing of Mexican migrants. Though America has not remembered the Middle Eastern migrants who once lived in the U.S.-Mexico borderlands, the legacy of border policing that targeted them continues to shape perceptions of the borderlands today.