Officially, relations between a so-called empire like China and her neighboring countries were frequently designated as “tribute relations”. In reality, however, much of the commercial, scientific and human intercourse that was going on not only in Asia but in the middle period and early modern world in general followed illegal or “private” paths and channels. Commodities, products, knowledge or human beings entered or left a country – or simply “crossed borders” – without the explicit permission or approval of a government or an official institution. This bilingual volume with English and Spanish essays investigates networks of unofficial, private or illegal commercial exchange activities and knowledge transfer, including the trafficking of people as well as human interaction that took place behind the official curtain of tribute and trade. The geographical focus definitely lies on East Asia, and almost every contribution at least relates to this macro-region. But it also introduces comparative examples from the Indian Ocean, the Asia-Pacific and the Atlantic and adjacent countries.