Preprint: Emlen, Nicholas Q., Rik van Gijn, and Sietze Norder. (Forthcoming.) The Andean-Amazonian interface: Sociolinguistic relations and areal-typological patterns. In Oxford Guide to the Languages of the Central Andes. Matthias Urban, ed. Oxford: Oxford University Press. 1 The Andean-Amazonian interface: Sociolinguistic relations and areal-typological patterns 1 Nicholas Q. Emlen Rik van Gijn Sietze Norder 28.1 Introduction The Andes is the longest terrestrial mountain chain in the world, extending around 7,000 kilometers from Colombia and Venezuela in the north to Tierra del Fuego in the south. However, it is also exceedingly narrow: in some places, the Pacific Ocean and the Amazon lowlands are less than 300 kilometers apart, as the crow flies. In those places, it is possible to travel in a car from the ocean to the Amazonian lowlands, ascending among snowy peaks above 5,000 meters, in a single day. The Andean chain thus compresses an extraordinarily diverse range of geographic and ecological zones, from deserts, forests, fertile valleys, and high wind-swept plateaus, into a long and narrow strip running the length of Western South America. Given these facts, it is no surprise that Western South American social networks have sometimes extended beyond particular ecological and geographic zones. This is partly a matter of mere proximity: people who live there are simply never far from a dramatically different environment. However, it is also a question of capitalizing on the region’s ecological diversity, which affords access to a broad range of resources that can be obtained through interregional trade, discontinuous landholdings, and other kinds of arrangements. This has brought people together both within and between the Central Andean highlands and the Amazonian lowlands in various places and at various moments in history. To be sure, such inter-elevational connections have varied in importance throughout the centuries and millennia, and some social formations can be understood as generally Andean or Amazonian phenomena without much reference to inter-regional connections. For instance, the initial Quechuan and Aymaran expansions and the Inka Empire were all broadly highland phenomena that involved Amazonia only to a relatively marginal degree, while none of the major lowland language families extend very far into the Andes (see e.g. Heggarty 2020c). However, it is also true that at some moments throughout history, smaller-scale social networks have spanned environments and mediated between speakers of various languages across the highlands and the lowlands. It is for this reason that a chapter about linguistic connections between the Central Andes and Amazonia belongs in a book about the Central Andean languages. On the one hand, any portrait of the Andean linguistic panorama must acknowledge, of course, the Andean-ness of the major Andean civilizations and language expansions; but any sufficiently 1 The authors thank Matthias Urban and Lev Michael for their helpful comments on an earlier draft of this manuscript. The research leading to these results received funding from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – project number UR 310/1-1 and from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement no. 818854 – SAPPHIRE).