Coin history - The Ming dynasty A.D. 1368-1644

Ming had 17 emperors of whom 10 cast coins. From the Ming to the end of the Qing, all emperors used only one reign title during each reign, and the emperors of this period are better known by their reign title than their temple name. The first emperor issued both bank notes and coins, but in 1394 he prohibited the use of coins. The next emperor followed this idea, and did not issue any coins. In 1408 the use of coins was again allowed by the third emperor. Paper money became inflated, and all payments were now done in coins and silver.
The Ming had to confront several rebellions and when the Ming had to flee from the Manzus and abandon their capital in Beijing in 1644, four princes retreated to the South and set up their own kingdoms, all issued their own coins. This period is called the Southern Ming, and it lasted from 1644 to 1662 when they were defeated by the Manzus, see the page on Southern Ming and Ming rebels.
The coins of Ming were never labeled Yuan Bao because the first emperor Zhu Yuanzhang’s name included the character yuan. This practice was followed for the remainder of the Ming dynasty (Peng p. 546). 
From 1505, during the Hong Zhi period, zinc was added to the alloy to make the casting process easier, and from now on, all coins in the Ming and the Qing were actually brass coins (Peng p. 547 confused tin and zinc).
The Ming dynasty cast comparatively few coins, and they were not as beautifully made as in earlier times. The majority of coins in circulation were actually Tang and Song coins. All this indicates that the Ming rulers did not regard coins with the same importance as before ( Peng p. 553).