The Union of the Iberian Crowns (1580–1640) promoted a wider cultural exchange between Portuguese and Spanish Asian settlements in Asia. This paper identifies the remarkable circulation of artisans and patrons and the development of new building techniques during this period, which allowed for a shared cultural dialogue that may be best described as forms of mestizage. So, it tries to address the mobility of patrons and architects, which helps explain the diffusion of techniques and models. The first case shows how cultural dialogue promoted new techniques from local traditions and materials, which were later used in neighbouring settlements. The second demonstrates the role these mixed solutions played in the creation of the image of a pure state, in the form of public palaces, a mestizo society, mainly in urban houses, and a local cultural resistance, keeping traditional housing forms in the native quarters. Thanks to this approach, the currently preserved built heritage can be seen not only as a European cultural transfer but also as the result of a fruitful global dialogue.