Ismailism is a subsect of Shia islam. It has a deep mystical angle which I will describe sometime later. The Ismaili Pirs who travelled in the subcontinent created a unique poetry style called Ginan. The syncretic tendency of Pirs also allowed their identification with the Bhakti movement. Even in the poetry you find lots of elements of Vedic and Islamic tradition. You can find more about it on the web. Here is beautiful Ginan sung by Abida Parvin.
Note: The Ginan starts at 1.10, the beginning of clip is also a famous and beautiful quawwali, Ali Maula.