Complex sentence: He learned the sitar from his mother Annapurna Devi, though he had not completed his "taalim" (training) with her when he left for USA with his father Ravi Shankar.
Split into simpler sentences: He learned the sitar from his mother Annapurna Devi. He had not completed his "taalim" (training) with her when he left for USA with his father Ravi Shankar.