Cowrie shells were the longest and most widely used currency of all times. In China they circulated as money already some 3000 years ago. From there they spread over Thailand and Vietnam into the Indian subcontinent; finally they came into use also on the Philippines, the Maldives, in New Guinea, the South Seas and in Africa. Along with other means of exchange cowries circulated in China until 1578. The Chinese writing system, which was developed in the 2nd millennium BC, uses the symbol for cowrie in words like "coin," "money," "buy," "value" and the like until this day. The symbol can also be seen on many Chinese cash coins.