Objective: This study aims to identify ethno mathematics in the Mbaru Niang traditional house of the Wae Rebo community, describe related mathematics concepts, and develop learning tools and learning trajectory for mathematics concepts contained in the culture of the Mbaru Niang traditional house. Theoretical framework: Ethno mathematics is all forms of mathematical activities that are culturally based and varied and can be done every day as needed (Rosa, 2011). Ethno mathematics is a group of ideas about the history of mathematics, the cultural roots of mathematics, the mathematics implicit in everyday rules, and the learning of mathematics (Weldeana, 2016). Ethno mathematics is defined as special ways used by a certain cultural group or society in mathematical activities (Sarwoedi, 2018). Ethno mathematics is mathematics applied by a particular cultural group and studies the relationship between mathematics (mathematics education) and the corresponding social and cultural background, i.e. how mathematics is produced, transferred, disseminated, and specialized in diverse cultural systems (Gerdes, 1994; Zhang & Zhang, 2010). Ethnomathematics is a learning approach that is carried out by teaching mathematics by linking mathematics with the nation's own cultural works and also involving the needs and lives of its people (Zaenuri, et al., 2018). Method: The research method used is descriptive qualitative research with an ethnographic approach. The researcher is the main instrument, and data is collected through observation, interviews, and documentation, data validity using source triangulation techniques. Furthermore, the data were analyzed to describe the research findings. Results and Conclusions: The results showed that there were mathematical activities in the construction of the Mbaru Niang traditional house. These activities include measuring activities with the concept of standard and non-standard units and designing activities related to the concept of geometry. Thus, the mathematical concepts contained in the construction of the Mbaru Niang traditional house can be developed by designing learning tools and learning trajectories that are in accordance with school mathematics. The culture of the Mbaru Niang traditional house is a source of learning mathematics that can be presented according to various contexts in learning mathematics. The study's findings contained several mathematical aspects of the culture of the Mbaru Niang traditional house. These aspects were the concept of geometry (in the form of a conical shape) and the concept of measurement (using non-standard measurements). The measurement concept can be applied to elementary school students, and cone geometry can be applied to junior high school. Thus, identifying and exploring Ethno mathematics in the Mbaru Niang. Implications of the research: Mathematics learning strategies that are oriented towards increasing student success in learning, respecting culture, enhancing cooperation and protecting the natural environment. This is done with the "ethno math" approach through learning in schools. Difficult math concepts can be unraveled with ethno math that is real around students and supported by teacher commitment in implementing learning in the classroom. Originality/value: The novelty of this research is the formation of an ethnomathematics model of mbaru niang that can be integrated in learning mathematics at school in order to provide advice for decision makers in this case teachers and government or education observers to be more pro-active in implementing learning in accordance with the culture around the student.