Most economists and historians today conceive of money in narrow terms – probably because they have grown up in the modern world and are used to our system of coins, paper notes, cheques and credit cards. Although economic historians are generally aware that some earlier societies (in Africa, Scandinavia and elsewhere) used other items as money, they do not usually pay much attention to these examples. Few realise that the government of China, governing an empire of some 60 million people during the Tang dynasty (618–907), implemented a complex financial system that recognised grain, coins and textiles as money. The government received taxes in coin and in kind, produced to specific standards (specific widths and lengths of textiles) that would then be redistributed, being used for official salaries and military expenses among other expenditures. Although some of the surviving evidence comes from the Silk Road sites of Turfan, Dunhuang and Khotan in northwest China (where the dry climate has preserved many documents and some actual examples of tax textiles), this multicurrency system was in use throughout the entire empire during the seventh to tenth centuries. At the time, Tang China was possibly the largest economy in the world, rivalled only by the Abbasid Empire (751–1258).