The Arabs were famous in the past for sailing the seas. The captain Ahmad ibn Majid, who lived in the fifteenth century, excelled among them. Ibn Majid wrote books on the science of the sea. In them he recorded what he knew about winds, currents, the positions of stars and the routes to ports. He wrote down notes from his long voyages so that those who came after him could use them. Sailors found their way by the stars at night. They measured the height of a star above the horizon to know their position. They used the compass when clouds hid the stars. This knowledge helped traders to sail between the coasts of the Gulf, India and East Africa. So trade grew, and peoples exchanged goods and ideas.

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