The main content of the biography of Xu Xiake revolves around his extensive travels across China during the Ming Dynasty. Xu Xiake, a renowned Chinese geographer, adventurer, and naturalist, embarked on a journey that spanned over 30 years. His travels were not merely for leisure but were driven by a deep curiosity about the natural world and a desire to document the geography, flora, fauna, and culture of the regions he visited.

Xu Xiake's biography highlights his meticulous documentation of his travels. He meticulously recorded his observations in his travelogue, "The Great Travel Diaries" (Daoyou Zhuan), which is considered one of the most comprehensive travelogues in Chinese history. The book provides detailed descriptions of the landscapes, people, and customs he encountered, offering a rich and vivid account of 17th-century China.

One of the key aspects of Xu Xiake's biography is his exploration of the natural world. He was particularly interested in geology, botany, and astronomy, and his observations in these fields were groundbreaking for his time. For example, Xu Xiake was one of the first to document the existence of coal beds and to recognize the importance of coal as a fuel source. His work in botany led to the discovery of several new plant species, and his astronomical observations were ahead of his contemporaries.

The biography also emphasizes Xu Xiake's dedication to his studies and his willingness to face hardships during his travels. He often traveled on foot, braving harsh weather conditions and rugged terrain. His determination and perseverance are evident in the vast amount of information he was able to gather and document.

The significance of Xu Xiake's biography lies in its contribution to the fields of geography, natural history, and anthropology. His work has provided invaluable insights into the state of China during the Ming Dynasty and has influenced the study of these fields for centuries. According to a study by the Chinese Academy of Sciences, Xu Xiake's travelogues contain more than 1,000 plant species and 600 animal species, making them a crucial resource for researchers.

In conclusion, the main content of Xu Xiake's biography is his extensive travels and meticulous documentation of his observations. His dedication to exploring the natural world and his willingness to face challenges have made him a legendary figure in the history of exploration and natural science.