Complex sentence: Others say that 12 "awlia" from Baghdad travelling to Chittagong discovered this island in the middle of the ocean and found no people, so they defined it as "Shunno Dwip" and which eventually became "Sandwip".
Split into simpler sentences: Others say that 12 Awlia from Baghdad who were travelling to Chittagong discovered this island in the middle of the ocean and found no people. They defined it as "Shunno Dwip" and which eventually became "Sandwip".