In the 1530s, the merchant and householder (vecino) Julián Gutiérrez resided in the small city of Acla, by the river Darién in the region of Castilla del Oro (today Panamá). In January 1535, the governor of Castilla del Oro described Gutiérrez as 'the key to pacify all the land' because 'without him the Indians did not come'. 1 But how could a sole Castilian foment peace among tribes more often at war (Helms 1979, 31-37)? The governor of the neighboring region of Cartagena, Pedro de Heredia, offered the key element to understand the equation. In a letter of December 1534, Heredia claimed that he needed better translators (lenguas) in order to pacify the land. In particular, Heredia sought out the interpreter, Isabel Corral, because 'the conquest and pacification of the land cannot be accomplished without her'. 2 Isabel Corral was an india ladina, the sister of an important cacique from the gulf of Urabá, and was married to Julián Gutiérrez. As the most prominent member of the cacicazgo, Corral 'stood in' for her whole kinship, to apply an anthropological concept (Sahlins 1985, 36), and her marriage to Gutiérrez incarnated an alliance between the elites of Castile and Urabá. Corral and Gutiérrez had travelled together, trading, along both sides of the gulf of Urabá from 1532 to 1536. Those travels, while facilitating commerce, also forged trust between the communities of Acla and the cacicazgo of Urabá and contributed, moreover, to the definition and redefinition of jurisdictional frontiers in the region. Isabel Corral, Julián Gutiérrez and Pedro de Heredia, as well as other agents considered in the following pages, illustrate how the Spanish Monarchy operated at the local level, through interactions among Castilians and, also, between Castilian and native populations. Following an interpretation of 'agent' as an individual or corporation that could engage in formal and informal relationships (Vermeir 2011), Isabel Corral became an indispensable informal agent of the Monarchy. A multiplicity of individual interests shaped the concept of common good at the local level, thus participating in a complex construction of loyalty and pertinence to the Monarchy. Isabel Corral did not occupy any official post in the administration or government, but her presence and intervention shaped new spaces of contact and relations that facilitated official endeavours in the region.The Spanish Monarchy in the Indies was built upon the interlocked foundation of cities -most of the time with only legal, not physical, existence-whose jurisdictions constructed the monarchy's political spaces from the bottom up. Considered in this way, the Spanish Monarchy does not refer to a monolithic institutional framework implemented by the Castilian Crown in the Indies. Instead, the Monarchy was a flexible