Working with Navajo Indian informants in Arizona, USA we became aware of the capabilities of children and adults to find their way in vast and clearly "chaotic" canyons. One thing we did was describe what people actually did and said about their ways to find the way back home in such contexts. A second one was to use these data in order to build a curriculum book for a bicultural school on the Navajo reservation. We start from this example to ask what the political choices are, which we confront when working with such material: how much mathematics (or is it Mathematics) is needed in daily life? And what mathematics should we promote or develop, without becoming colonialist again? In Section 2, we discuss the meaning and the status of ethnomathematics, proposing that it would be the generic category which allows for a more systematic and comparative study of the whole domain of mathematical practices. In Section 3, we introduce the concept of multimathemacy (after multiliteracy) to discuss the political agenda of ethnomathematics. We argue that multimathemacy should be the basis of the curriculum in order to guarantee optimal survival value for every learner.