In the early 11th century Tarikh al-Yamini, the Arab historian Al-Utbi recorded that in 1001 the armies of Mahmud of Ghazna conquered Peshawar and Waihand (capital of Gandhara) after Battle of Peshawar (1001), "in the midst of the land of Hindustan", and captured some 100,000 youths. Later, following his twelfth expedition into India in 1018–19, Mahmud is reported to have returned with such a large number of slaves that their value was reduced to only two to ten dirhams each. This unusually low price made, according to Al-Utbi, "merchants from distant cities to purchase them, so that the countries of Central Asia, Iraq and Khurasan were swelled with them, and the fair and the dark, the rich and the poor, mingled in one common slavery". Elliot and Dowson refer to "five hundred thousand slaves, beautiful men and women.". Later, during the Delhi Sultanate period (1206–1555), references to the abundant availability of low-priced Indian slaves abound. Levi attributes this primarily to the vast human resources of India, compared to its neighbors to the north and west (India's Mughal population being approximately 12 to 20 times that of Turan and Iran at the end of the 16th century).