Why could Hutu and Tutsi identities be fluid in precolonial Burundi?

In precolonial Burundi, the identities of Hutu and Tutsi were fluid rather than rigid, primarily because they were defined more by socioeconomic status and societal roles than by fixed ethnic categories.12

Several factors contributed to this fluidity:

• Socioeconomic Status: Traditionally, Tutsi were associated with cattle ownership—a primary symbol of wealth—while Hutu were agriculturalists. Because these roles were tied to economic standing, a wealthy Hutu could be identified as a Tutsi, while an impoverished Tutsi might be identified as a Hutu.132
• Cultural Integration: Both groups shared the same language, Rundi, and practiced frequent intermarriage over the centuries, which blurred physical distinctions. While the Tutsi were generally presumed to be taller and lighter-skinned, these physical traits were not always apparent or consistent across the population.1342
• Social Structure: The presence of a princely class, the ganwa, helped mediate between the king and the masses, keeping ordinary Hutu and Tutsi on a relatively equal footing within the broader social hierarchy.13

These flexible identities were later hardened into rigid ethnic categories by colonial administrators who mistakenly assumed that ethnicity could be clearly distinguished by physical characteristics.5