In Shanghai, this complexity represented a microcosm of the complicated economy existing elsewhere along the China coast. The Chinese reckoned in weights of silver, which did not necessarily correspond to circulating coins. One important unit was a tael, a measurement of weight with several different definitions. These included: Customs Taels (for foreign trade), Cotton Taels (for cotton trade), etc. Shanghai had its own tael, which was very similar in weight to the Customs Tael and therefore popular for international business. China also had a mixture of coins, including Chinese Copper Cash coins and Mexican dollars. Paper money was first issued by European and North American colonial banks (one British colonial bank known as the Chartered Bank of India, Australia, and China at one time issued banknotes in Shanghai that were denominated in Mexican dollars).