The Turks claim that Ahmad ibn Majid was an Omani. Other researchers claim Vasco Da Gama met Majid in West Africa. The information about Ahmad ibn Majid of West Africa , comes from T.A. Shumusky, Tri neizuesttruie totsii Akhmada ibn Madzhida lotsmana Vasko da Gamui ( Moscow, 1957), and R.A.G. Bazan, Latin America the Arabs and Islam,,Muslim World, (1967) pp.284-292.
The Turk account of Majid , comes from The Ottoman conquest of the Yemen , this book discusses the Portuguese entry into the Indian Ocean . It was written 50 years after the Da Gama voyage. This authors claim that Majid was drinking with a Frank merchant and Da Gama, and gave him the secrets to navigation in the Indian Ocean this seems highly unlikely for two reasons. First, where did this drinking take place, between Da Gama, the German and Majid; was it in Oman or East Africa. This sounds illogical because how did Da Gama, get to Oman, if he didn’t know the way until he was instructed by Majid in navigation of the Indian Ocean.
Secondly, Da Gama made it clear he got an Indian pilot at Malindi to guide him to India. Ask yourself, how would Da Gama have known he would need an Indian pilot to reach India, because they used the Monsoons. It was knowledge of the monsoons that made Da Gama's voyage to India smooth, but his return to Africa without a guide horrendous.
This makes the Turk story about Majid unlikely. Since it was written 50 years after the voyage of Da Gama,the Turks could have gotten a copy of Majid’s book by this time, and made up the story about the Omani origins of ibn Majid.
I believe that Da Gama learned about the West Indies and Indian Ocean trade from a West African named Ahmad ibn Majid, because of 1)the Treaty of Tordesillas, and 2) Da Gama being chosen to lead the expedition to India.
This would also explain how Portugal got to Brazil in 1500, at the same time the Spanish arrived.
Secondly Da Gama was a junior naval officer, but he was given Command of the expedition to India. This was strange because they already had an experienced officer who had sailed around South Africa.
Bartolome Dias was already a veteran navigator when had rounded the Cape of Good Hope in South Africa 10 years earlier. But he was not given the Command of the expedition to India, the Command of this expedition was given to Da Gama . We must assume that King Manuel I , felt Da Gama had nautical knowledge.that would help him to be successful in this expedition. Da Gama must of had some special knowledge about trade in the Indian Ocean region that would make him more successful than Dias. This information may have been what he learned about navigation and trade in the Indian Ocean from ibn Majid.
In summary I believe that Da Gama learned about trade in the West indies and Indian Ocean from a West African named Ahmad ibn Majid. And because of this Knowledge the Portuguese were able to gain Brazil, and Da Gama was given Command of the expedition to India.