When him, his dad, and his uncle reached China by passing mountains, the Gobi desert, and Persia they visited Kublai Khan. They gave him presents.
After 17 years, of working with Khan they left. In 1298 Marco joined the war against the Mongols, then got captured and spent a year in jail.
During his time in prison, he met a writer named "Rustichello." Rustihello wrote a book about Marco Polo's journey, and it, later on, was passed around people of Eurpoe, and the book became well-known.