Later he spent much time collaborating with world musicians , notably Malian singer Salif Keita , Tibetan monk Lama Gyurme and Senegalese singer and percussionist Youssou N'Dour .
Later he spent much time collaborating with world musicians , notably Senegalese singer Youssou N'Dour , Tibetan monk Lama Gyurme and Malian singer and percussionist Salif Keita .