The history of the postage stamps and postal history of China is complicated by the gradual decay of Imperial China and the years of civil war and Japanese occupation in the 1930s and 1940s. In modern times, postal delivery is handled by China Post. Early history Regular government postal service is known from the Zhou dynasty in the 1st millennium BC. During the Yuan dynasty under Kublai Khan in the 12th century, China was integrated into the much larger Mongolian Örtöö system. Marco Polo reported that there were 10,000 post stages during that time. In addition, private letters were carried by the Min Hsin Chu, a system of letter guilds (hongs). Later the 1727 Treaty of Kyakhta with Russia provided for the first regular exchange of mail. Qing Dynasty Although postal service in China goes back some 2,500 years, modern postal services were not established until 1877 by the Qing government. A policy of isolation was forcibly ended in the 19th century by the Opium War and the subsequent opening of treaty ports; several nations opened foreign post offices from 1844 on. This expanded to involve dozens of cities, mostly on the coast, along the Yangtze River, and in the far south. Shanghai organized its own Shanghai local post in 1865. In the same year, the Irishman Robert Hart developed a mail service for the Imperial Maritime Customs, initially to carry consular mail to and from treaty ports. This service was opened to the public on 1 May 1878, and China's first postage stamps, the "Large Dragons" (), were issued to handle payment. The stamps were inscribed "CHINA" in both Latin and Chinese characters, and denominated in candareens. Initially, all mail to foreign destinations went through Shanghai, but by 1882 there were twelve post offices. On 20 March 1896, an edict directed that the Customs Post become the Imperial Postal Service effective 1 January 1897; the Min Hsin Chu was shut down, as well as the Shanghai local post, and postal system adopted cents and dollars as the units of currency. Through the first half of 1897, new stamps were unavailable, and so the existing stock was surcharged in cents, with several variants distinguished by philatelists. Revenue stamps were surcharged as well. The first new stamps, inscribed IMPERIAL CHINESE POST went on sale 16 August 1897. The twelve values, ranging from 1/2c to $5, were lithographed in Japan. The low