Millet is one of the first agricultural crops appeared on the Taiwan island in the Neolithic. However, its share in the diet of the ancient population of the island compared to another culture, i.e. rice, remains rather unclear. Today's indigenous peoples have legends that emphasize a special attitude to millet as the first crop that appeared in their land. This paper considers the results of scientific investigations held in the south of the Taiwan island, Taitung County, in summer 2019. The investigation is focused on the ritualism of the Jilou sub-ethnos (???), which is a part of the Rukai (???), the Taiwanese highlanders (???). Many aspects of sacred life of the island peoples are related to the millet culture, and traditional calendar is based on its production cycle. During sowing and harvesting, a number of ritual rules and restrictions are strictly applied. Thus, everything related to the millet production falls into the sphere of religion. Millet cakes and wine to thank the deities and ancestral spirits always accompany the most important event of the year, the Harvest Festival. Archaism of the Taiwan aboriginal traditional culture makes the investigation of their agricultural practices very important not only for the island, but also for the entire Southeast Asia in general. This investigation, which covers both ethnography and archaeology, seems to be extremely important for studying the relic signs of traditional food preferences of indigenous peoples, rooted in the Neolithic.