When did the lost wax casting of Chinese bronzes begin?

In the early Warring States period, the lost wax method was invented to cast bronzes. The so-called lost wax method is to use beeswax as a model, fill the clay core with refractory inside and outside, and lay it in the outer mold. After heating and baking, the wax pattern falls off, and then copper liquid is poured to cast the object. This method can produce fine patterns and complex and rich shapes. Zun He Pan unearthed from Tomb No.2 of Zeng Hou in Suixian County, Hubei Province is the earliest lost wax casting bronze ware.