It was usually said that the big bell had been cast in the second year of the reign of Yongle (1404). Another erroneous argument is that the big bell was cast after the death of Emperor Yongle. There is no scientific ground for the two arguments. The former argument is based on the verse "cast in the second year of Yongle" in the Ode to the Big Bell written by Shen Deqian, a poet of the Qing Dynasty. When we investigated in Nanjing the ties between the Hongwu Bell and the Yongle Bell, we learned from historical data that when Shen Deqian arrived in Nanjing, the Hongwu Bell there had been lying on the ground for many years. Shen Deqian formed a wrong opinion that the bell had been cast in the second year of the reign of Yongle. The bell was located northwest of the Jiming (Cockcrow) Temple, Nanjing. In the Ode to the Big Bell, Shen Deqian described the bell of the Big Bell Temple in Beijing and then wrote about the ties between the bell in Nanjing and the bell in Beijing:

     "I think of the place northwest of the Cockcrow.

             The big bell is sleeping on the earth overgrown with weeds.

             It was cast in the second year of Yongle

             To take Heavenly credit for merits at two places."

Later people took this as the only ground to determine the year when the big bell of the Big Bell Temple was cast. They drew the wrong conclusion that the bell was cast in the second year of the reign of Yongle.

We have learned from many historical documents that the Yongle Bell was "cast in the days of Emperor Wen (namely, Emperor Yongle)," "the bell was cast in the days of Emperor Chengzu (the dynastic title of Emperor Yongle)," and the Yongle Bell was "an imperial bell of Emperor Wen." Cast on the east wall of the Yongle Bell was "made on an auspicious day of the reign of Yongle of Great Ming," an inscription indicating that the bell was made by imperial order. It is thus clear that the bell was cast undoubtedly during the reign of Yongle.

Is it possible to reach an opinion on the exact year when the big bell was cast?

In 1980, staff members of the museum found from the Jiaxing Edition of Tripitaka that the 188th case of the book was the Sutra of the Names of Buddha, Bhagavat, Tathagata, Bodhisattva, Arya and Miracle - working Buddhists (thereafter referred to as the Sutra of Names). The sutra consists of 40 fascicles. The first 20 fascicles (to-tailing more than 100,000 characters) were cast on the main part of the Yongle Bell. The sutra was completed in the 15th year of the reign of Yongle by Emperor Yongle's order. The preface and postscript of the Sutra of Names were written in the 15th year of the reign of Yongle. The block - printed edition of the Sutra of Names made by Emperor Yongle's order was found later. Its content is identical to what has been collected in the Jiaxing Edition of Tripitaka. So the Yongle Bell should not have been cast before the 15th year of the reign of Yongle. Judging from the technological level of casting and the difficulties involved in the work, we may conclude that it took at least two or three years to prepare the mould of the Yongle Bell. The casting was done at one stroke, but the whole process from the first-phase preparations to the later - stage work required three to five years for the birth of such a superb big bell. An acceptable assertion is that "the Yongle Bell was cast around the 18th year of Yongle (1420)."