1. Shared cultural traits: This encompasses a wide range of elements, including language, religion, traditions, customs, values, beliefs, and historical experiences. These shared cultural traits often create a sense of belonging and common identity among members of the group.

2. Common ancestry: While not always explicitly stated, ethnic groups often trace their origins back to a shared ancestral group. This common ancestry can manifest in a variety of ways, such as shared genetic markers, historical narratives, and geographical origins.

It's important to remember that these two aspects are not always clearly defined or easily categorized. Ethnic identities are complex and fluid, and individuals may identify with multiple ethnicities depending on their personal experiences and cultural background.