Final answer:
Kunqu is the first well-defined Chinese opera form that emerged during the Song Dynasty in the tenth century.
Step-by-step explanation:
The first well-defined Chinese opera form, known as Kunqu, appeared in China during the Song Dynasty in the tenth century. Each regional opera form in China has its own characteristics and history, and Kunqu is particularly noted for its blend of instrumental music, vocal performance, and stylized action. Chinese operas like Kunqu, have evolved through dynastic changes from the Song period, to the well-known forms such as Peking Opera amongst others later on. These developments reflect the rich and diverse cultural heritage of China, where art forms like opera are highly esteemed and closely related to the values and aesthetics of the society.