According to the "Memoirs" of Xuanzang, there were about a hundred Buddhist convents in the city or its vicinity at the time of his visit there in the 7th century. There were 3,000 monks and a large number of "stupas" and other religious monuments. The most remarkable "stupa" was the Navbahara (Sanskrit, Nav Vihara: New Monastery), which possessed a gigantic statue of Buddha. Shortly before the Arab conquest, the monastery became a Zoroastrian fire-temple. A curious reference to this building is found in the writings of the geographer Ibn Hawqal, an Arab traveller of the 10th century, who describes Balkh as built of clay, with ramparts and six gates, and extending for half a parasang. He also mentions a castle and a mosque.