Musa was an Italian slave-girl who was given to the Parthian monarch Phraates IV (r. 37 BC - 2 BC) as a gift by the Roman Emperor Augustus (r. 27 BC - 14 AD). Phraates IV received her around the time a treaty was made in 20 BC, whereby he received his kidnapped son in exchange for several Roman legionary standards captured at Carrhae in 53 BC, and the surviving Roman prisoners of war. The Parthians viewed this as a small price to pay to regain the prince. Emma Strugnell (2008) has suggested that Augustus may have sent Musa in an attempt to obtain information or influence the Parthian king to the advantage of the Romans.

According to the Parchments of Avroman, Phraates IV already had at least four other queens at that time: Olennieire, Cleopatra, Baseirta and Bistheibanaps. Musa quickly became queen and a favourite of Phraates IV, giving birth to Phraataces (Phraates V) about 19 BC. Seeking to secure the throne for her son, she convinced Phraates IV in 10/9 BC to send his four first-born sons to Rome in order to prevent conflict over his succession.