The word ovoo means “heap” or “pile” in Mongolian. The ovoo are highly significant features of Inner Asia’s sacred landscape and are present in Mongolian-speaking areas (Mongolia, Inner Mongolia, Buryatia, Kalmykia), as well as in Turkic-speaking Tuva. Depending on the area and the immediate environment in which they are erected, the ovoo have various features, from simple round heaps of stones and branches to more elaborate structures, such as a circular mound of stones with a central pole topped with brushwood and decorated with prayer flags and/or colored ribbons. Built by local people for centuries, the ovoo serve as territorial markers and ritual altars. Ovoo found on ritually significant mountains are worshipped annually by a given social group (people from the same village [sum], a clan, an ethnic group, etc.) to propitiate the various divinities of the land, ensuring protection and prosperity. Like other ritual activities, ovoo worship was banned in Mongolia, China, and Russia as a result of communist antireligious polices. In the early 21st century, ovoo worship constitutes a revived religious practice in all three countries and has drawn the attention of politicians and scholars.