How did the Romans know that Cleopatra was black?

 There is no concrete evidence to suggest that the Roman population knew Cleopatra as "black" in the modern sense of the term. The concept of race and skin color categorization was different in the ancient world and not based on the same rigid binary system as today.

Descriptions of Cleopatra's appearance by Roman writers are scarce and ambiguous. Some mention her beauty and charm, while others imply a non-Roman appearance. However, these descriptions often used vague terms like "exotic" or "eastern," not specifically referring to skin color.

Roman art and sculptures depicting Cleopatra further complicate the issue. While some portray her with darker features, others showcase a more conventionally Roman appearance. This inconsistency suggests that the Romans didn't have a singular, clear-cut perception of her ethnicity.

Instead of focusing exclusively on skin color, it's more helpful to understand Cleopatra's identity through the lens of her cultural background and political context. As a Macedonian Greek ruler of Egypt, she belonged to a distinct cultural and political sphere. This distinction, rather than her skin color, likely played a larger role in shaping Roman perceptions of Cleopatra.

Therefore, while there may have been some awareness of Cleopatra's non-Roman ancestry, concluding that the Romans knew her as "black" in the modern sense is inaccurate and misleading due to the differing racial classifications of the time. To gain a deeper understanding of Cleopatra's identity and how she was perceived by the Romans, we must delve into the nuances of cultural and political dynamics rather than relying solely on skin color as a defining factor.