The trumpet in its earliest form was invented thousands of years ago, with evidence of metal trumpets dating back to around 2000 BCE in ancient Egypt. Early trumpets were signaling instruments used in religious ceremonies, military, and other civic purposes rather than as musical instruments in the modern sense. These primitive trumpets were often made from animal horns, wood, or metal and played using natural harmonics. The trumpet began to be considered a true musical instrument with the development of the natural trumpet in the late Middle Ages and early Renaissance (around the 14th and 15th centuries). The modern valve trumpet, capable of playing a full chromatic scale, was invented in 1820 by German horn players Heinrich David Stölzel and Friedrich Blühmel with instrument maker C.F. Sattler, revolutionizing trumpet playing and music composition for the instrument.