Visit the ports in desert. Trade, make profit. Follow the quests given by the governor. After making enough money renew your ship, and discover the depths of the desert.
If you run out of money you will get bankrupt.
In case you need a tip, you can have a cup of Turkish coffee from the coffee shops in ports. They will tell you where to buy goods and where to sell them for the best profit. You will have six goods; wood, egg, fish, meat, tea and iron. There will be ancient port cities such as Halicarnassos.