Omnium Gentium Mores, Leges et Ritus
Originally composed in 1520, Johann Boemus's tract on the "Manners and Customs of All Nations" enjoyed immense popularity as the first encyclopedic ethnography produced in Early Modern Europe. Included in Boemus's authoritative manual was a treatment of Prester John, the white-skinned king of Ethiopia. The text went through several editions and was translated into a number of other European languages, including William Waterman's English translation in 1555.
Check out the 1561 printing or jump to the English translation, Fardle of Facions.