When did composers start composing?

Composers have been composing music since the earliest known musical traditions. The earliest known composed music dates back to around 3500 BC in ancient Mesopotamia, where cuneiform tablets were used to notate music. In the 13th century, the concept of musical composition began to take on a more modern form, with the emergence of polyphonic music and the development of notation. By the 16th century, composers had begun to write instrumental music, which led to the development of opera, oratorio, and other genres.