The combination of language-internal and language-external approaches means that historical sociolinguistics is an interdisciplinary way to work. Still, it is clear that the goal of our research is to learn more about language and language use as such, which means that historical sociolinguistics is a branch of linguistics. This chapter examines the importance of language for creating commercial networks, Francesco Guidi-Bruscoli emphasizes the importance of Italian as a trade language in the southern part of Europe, and Braunmuller and others have shown that Low German played this role in the north. When discussing the language of trade as such, however, we commonly refer to the communication between more or less equal trade partners. A linguistic hierarchy may be drawn with Latin on the top, Italian and Low German as the second highest, and other vernaculars at the bottom.