Central Asia stretches from the Caspian Sea in the west to China in the Eastern . Most trade routes through China were ones for the Silk Road. There, they traded mostly silk, iron, mirrors, weapons, ivory, paper, gunpowder, medicine, etc. So it's possible that the Muslims are traveling on the Silk Road, on their way to India. Why India? Because when entering India, you'll see sand, and later on grass. Persia, Egypt, and Arabia are all packed with sand. There's barely any grass. So in conclusion, The Muslims are traveling from China to India on the Silk Road, on their way to trade
silk, iron, mirrors, weapons, ivory, paper, gunpowder, medicine, and other items.