Who discovered the Indian Ocean and how?

After the 7th c. AD, when the Arabs conquered all of northern Africa, the Arabian Peninsula and the Middle East, all routes to the Indian Ocean were closed to Europeans. And only 8 centuries later, in the 15th century, the Portuguese and Spaniards began to look for ways to India and China, from where Arab traders carried goods to Europe. For this, the Portuguese began to prepare ships and crews for long voyages, to create maps of the African coast. Bartolomeu Dias was the first to swim across the Atlantic and enter the Indian Ocean bypassing Africa.