Nalanda University, an ancient center of higher learning in India, was renowned for its extensive collection of knowledge and attracted scholars from various regions. Among the list of scholars who visited Nalanda, Xuan Zang, a Chinese Buddhist monk, pilgrim, and scholar, is well-known for his journey to India.

Let's analyze why Xuan Zang is the correct answer:

1. Xuan Zang, also known as Hsuan Tsang, traveled to India in the 7th century during the reign of the Tang dynasty. He embarked on a journey to collect Buddhist texts and to gain knowledge about Buddhism directly from its birthplace.
2. During his stay in India, he spent several years at Nalanda University, where he studied and interacted with other scholars. He also documented his experiences and observations about the architecture, educational practices, and life at the university.
3. Xuan Zang's travelogue, "Great Tang Records on the Western Regions," provides detailed accounts of Indian culture, religion, and academia during that period.
4. He is credited with enhancing Sino-Indian cultural ties and significantly contributing to the spread of Buddhism in China by translating numerous Indian scriptures into Chinese.

Given these points, Xuan Zang (China) is the correct answer as he carried back scriptures from Nalanda University and wrote about its architecture and learning.