Concurrent with the song led by Moses, Miriam led all the women together in song and music. According to the Sages, while Miriam was still in Egypt she prepared the musical instruments that she would eventually use at the sea.

“Miriam the prophetess, sister of Aaron, took the drum in her hand, and all the women came out after her with drums and musical instruments” (Exodus 15:20). From where did the Israelites have drums and musical instruments in the wilderness? The righteous were certain that the Holy One, blessed be He, would perform miracles and mighty acts when they emerged from Egypt, and they prepared drums and musical instruments for themselves. (Mekhilta deRabbi Yishmael, Beshalah, Mesekhta deShira 10)