Beliefs of an ethnic group are collectively called the group's:

The beliefs of an ethnic group are most accurately referred to as the group's culture. Culture encompasses the shared values, norms, practices, beliefs, and symbols that characterize a particular group. It reflects how members of the group understand the world and interact with each other and their environment, creating a collective identity.

While traditions, customs, and history also play important roles in defining an ethnic group, they are more specific aspects of culture. Traditions refer to practices passed down through generations, customs denote specific behaviors or rituals that are characteristic of a group, and history involves the events and narratives that have shaped the group over time. Culture, in contrast, is a broader term that encapsulates all these elements, including beliefs, values, and social practices, making it the most appropriate choice in this context.