Rice is a staple food raw material for people in West Kalimantan. One of the activities of planting rice is in Tunang village, Mempawah Hulu sub-district, Landak district, West Kalimantan, which is influenced by the habits of the population and geographical location. In a series of processes for growing rice in the village, it is inseparable from culture which can be linked to mathematics (ethnomathematics). For this reason, the purpose of this study is to find out the ethnomathematics of the cultivation of mountain rice or monotonous rice by the Dayak Kanayatn tribe, precisely Dayak Ahe. This study uses a qualitative approach with a descriptive method. Data collection techniques used literature studies, surveys, and interviews. The results showed that rice farming activities in the Dayak Ahe community were slashing land (nabas uma), felling (nabang), burning fields (nunu uma), cleaning fields after being burned (marasehan uma), grazing (nugal uma), grazing (ngarumput). uma), and rice harvest (bahanyi). During this process, there are also ritual ceremonies carried out, namely the Nabo' Panyugu Nagari ceremony, Nabo' Panyugu Tahutn / Riding Dango ceremony, Ngawah ceremony, batanam rice ceremony (which consists of the ngamalo ceremony, Lubakng Tugal ceremony, and the rice disease ngiliratn ceremony). Ngaladakng buntikng rice ceremony, ngabati' ceremony, and ngaleko ceremony. This series of processes contains ethnomathematical values, namely points and lines, spatial shapes, flat shapes, numeration, and symmetry of shapes.