What musical instruments were used in ancient Greek times?
The Greeks had a variety of instruments, such as the flute, the lyre, the harp, drums, cymbals, and castanets. There were also several horns (wind instruments). A detailed list can be found at: http://www.mlahanas.de/Greeks/Music.htm.
It was Pythagoras, famous for his geometric theories, who also figured out the ratio for tones in a musical scale.