Sultan Mahmud of Ghazni was the ruler of Afghanistan. He ruled from A.D 997 to 1030 and extended control over parts of Central Asia, Iran and north-western part of the subcontinent. He raided the subcontinent almost every year. His later invasions were specifically directed to temple towns, including that of Somnath, Gujarat, as Indian temples were depositories of great wealth. Much of the wealth that Mahmud carried away was used to create a splendid capital city at Ghazni. He entrusted a scholar named al-Biruni to write an account of the subcontinent. This Arabic work, known as Kitab-al Hind remains an important source for historians.