When did the concept of an orchestra start?

The concept of an orchestra as a large ensemble of instruments playing together can be traced back to the 16th century, when the instrumentalists at court began to be organized into more formal groups. In the 17th century, the orchestra gradually evolved as an independent ensemble, with its own identity and repertoire. By the end of the 17th century, the term "orchestra" was being used to refer to the ensemble of musicians who played in an opera or ballet, and the concept of the modern symphony orchestra had begun to emerge.