A shortage of copper made it difficult to produce an adequate supply of coins. In 955, an Edict banned the holding of bronze utensils:  From now on, except for court objects, weapons, official objects and mirrors, and cymbals, bells and chimes in temples and monasteries, all other bronze utensils are banned ... Those who hoard more than 5 jin, no matter how much the amount, will be executed. Those who abetted them will be exiled for two years, followed by labour service for one year. Those around them will suffer 100 strokes of the cane. Informers will be rewarded with 30 strings of cash. The south enjoyed somewhat better political and economic conditions, and saw an advance in trade. A great variety of coinage, including large and base metal coins, was issued in this area. Kai Ping tong bao () and also a Kai Ping yuan bao coins could have been issued by Zhu Wen when he overthrew the Tang in 907. However, only a few specimens of each coin are known, and one of each is shown in China National Museum and China History Museum. Some authorities doubt their authenticity. Tian Cheng yuan bao () were issued by Emperor Ming in the Tiancheng period (926–929). Tian Fu yuan bao () were issued by Emperor Gao Zong in the Tianfu period from 938. From 939, private casting was permitted for a few months, resulting in coins of adulterated alloy. Han Yuan tong bao () coin's pattern is based on the Kai Yuan. In 948, during the reign of Emperor Gao Zu, the President of the Department of Imperial Feasts requested permission to set up a mint in the capital (Kaifeng, Henan). There is no specific record of casting Han Yuans. Zhou Yuan tong bao () coins were issued by Emperor Shi Zong from 955. The pattern is also based on the Kai Yuan coin. They were cast from melted-down bronze statues from Buddhist temples. When reproached for this, the Emperor uttered a cryptic remark to the effect that the Buddha would not mind this sacrifice. It is said that the Emperor himself supervised the casting at the many large furnaces at the back of the palace. The coins have amuletic properties because they were made from Buddhist statues, and are particularly effective in midwifery – hence the many later-made imitations. Issued by Wang Jian (907–918).