The location is Madagascar.
Explanation:
In the eighth chapter of "The travels of Marco Polo", according to the excerpt given here, the location that has been talked about is Madagascar. It is the island which is about a thousand miles south from Socotra and it is one of the biggest and the best island in the whole wide world.
The people who live on this island worship Mahomet and have four sheikhs. These four sheikhs have the authority of this island. The circumference of this island is about four thousand miles and it is the place where more elephants are bred than any where else in the world and not many tusks of the elephants are sold.