Khusraw, a Persian poet, philosopher, scholar, and traveler, is considered one of the great writers of Persian literature. His most famous work is the Safarnama, an account of his seven-year journey through the Islamic world, during which time he made pilgrimages to the holy shrines of Mecca and Medina and visited many cities, including Jerusalem and Cairo. The work stands out as the most authentic account of the Islamic world at that time. He traversed what distance in those seven years?
Source: Nasir Khusraw Embarks on Seven-Year Middle East Journey (1046) (http://encyclopedia.thefreedictionary.com/Nasir+Khusraw)