a large number of Cambebas and Hutten was severely wounded. In 1560 Pedro de Ursúa even took the title of Governador del Dorado y de Omagua. Alexander von Humboldt referred to the supposed location of the mythical golden city, "El Dorado de las Omaguas", as being "between the sources of the Rio Negro, of the Uaupes (Guape), and of the Jupura or Caqueta." The Spanish explorer Francisco de Orellana, who was the first European to navigate the full length of the Amazon River (1541–42), reported densely populated regions running hundreds of kilometers along the river, although the people there left no lasting monuments, possibly because they used local wood as their construction material. While it is possible Orellana may have exaggerated the level of development among the Amazonians, their semi-nomadic descendants are distinguished by having a hereditary yet landless aristocracy, a historical anomaly for a society without a sedentary, agrarian culture. This suggests they once were more settled and agrarian but became nomadic after the demographic collapse of the 16th and 17th century, due to European-introduced diseases such as smallpox and influenza, while still maintaining certain traditions. Moreover, many indigenous people adapted to a more mobile lifestyle in order to escape colonialism. This might have made the benefits of terra preta, such as its self-renewing capacity, less attractive—farmers would not have been able to employ the renewed soil as they migrated for safety. Gaspar de Carvajal, who accompanied Orellana, included a description of the Omaguas in his 1542 work Relación del nuevo descubrimiento del famoso río Grande que descubrió por muy gran ventura el capitán Francisco de Orellana ("Account of the recent discovery of the famous Grand river which was discovered by great good fortune by Captain Francisco de Orellana"), discussing their culture, diet, housing, settlement patterns and political structure. Cristóbal de Acuña, who accompanied Pedro Teixeira's 1637-38 expedition along the length of the Amazon, commented extensively on the colorful woven clothing used by the Omaguas, writing that ...all of them go about decently dressed, both the men and women, who weave...not only the clothes they need but also other items traded with their neighbors...they make very beautiful cloth, either woven in different colours or painted so perfectly that it is almost impossible to distinguish between them... Most early chroniclers remarked on the Omagua practice of flattening the head, a practice common among indigenous South American tribes. Acuña described it