Sisters Mahsa and Marjan Vahdat were both trained in classical Persian singing by master musicians in Iran as well as in regional and traditional Iranian music. After the Islamic Revolution in 1979 in Iran, public female singing was banned and even some years after the revolution female singers can only perform for women-only audiences or alongside a male voice, and can never perform solo in public. But many female singers in Iran have continued singing regardless, as have Mahsa and Marjan, who give private concerts in Iran but mostly perform outside of the country.

Their repertoire is inspired by regional and traditional music from Iran with their own musical expression; their lyrics are mostly mystical and love poems by great Persian poets like Hafez, Rumi, Saadi, who lived several centuries ago, as well as contemporary Iranian poetry speaking about Iranian society. An active campaigner for human rights, Mahsa gives numerous benefit concerts and, with Marjan, is also one of the ambassadors of Freemuse, an independent international organisation advocating freedom of expression for musicians and composers worldwide. She has attracted considerable attention recently with her work on the record Lullabies from the Axis of Evil.