The Ming Dynasty saw rapid development of the iron-smelting industry. During the Hongwu reign (1368-1398), iron-smelting companies run by the government numbered 13. The iron-smelting company in Zunhua (now Zunhua County, Hebei Province), for instance, boasted a smelting furnace measuring over 6 m high, 4 m deep, more than 2 m in diameter inside, and more than 3 m in diameter outside. It produced not only pig iron but also wrought iron and steel. The government used steel primarily for making household utensils and weapons. The sword in the picture, a relic of the Ming Dynasty, is still sharp, pliable, and not too rusty, indicating the advanced technical level of the Ming Dynasty in steel-making.