Why is Il milione not a complete autobiography of Marco Polo?

Il milione is not a complete autobiography because it was never intended to be one. Instead, it was conceived as a vast, impersonal cosmography—originally titled Divisament dou monde ("Description of the World")—designed to serve as a comprehensive reference work on Asia.1

Several factors contribute to its nature as a work of travel literature rather than a personal memoir:

• Scope and Focus: The book prioritizes descriptions of geography, trade, and foreign cultures over personal recollections, often leaving Marco Polo’s own personality and specific activities elusive.12
• Collaborative Influence: The text was dictated to Rustichello, a writer of romances, who infused the work with his own stylistic preferences and standardized descriptions, particularly regarding battles.31
• Editorial Alterations: Before the invention of printing, the text underwent extensive changes. Scribes and translators frequently added, subtracted, or bowdlerized content, leading to approximately 140 different manuscript versions that vary significantly in authenticity.1
• Inclusion of Secondhand Accounts: Polo frequently included descriptions of regions he likely never visited himself, relying instead on information from relatives or acquaintances.1

Ultimately, Polo himself reportedly remarked on his deathbed that he had told barely half of what he had actually seen.3