By the mid 15th century, Prince Henry 'the navigator' of Portugal was encouraging voyages of exploration around the african coast. He hoped to find a sea route to the east, as well as the christian kingdom of the legendary Prester John (or 'priest-king') of Abyssinia. With the rise of the Ottoman Empire in 1453, all goods from the east, including the increasingly valuable spices, now reached Portugal via potentially hostile Muslim countries.
In 1487, Prince Henry's successor, King John II, despatched two expeditions to the East led by Bartholomew Dias and Pedro da Covilhan: one by sea around the southern tip of Africa, the other overland through Egypt. In 1497, another Portuguese navigator, Vasco da Gama, encouraged by the reports of Dias and da Covilhan, rounded the Cape of Good Hope and sailed northwards up the coast of east Africa, on the way to India. He passed Zanzibar and landed at Mombasa, where he received a hostile reception from the sultan. But he got a warm welcome in Malindi, an old enemy of Mombasa. Da Gama built a pillar of friendship on the shore at Malindi and employed an Omani navigator called Ahmed bin Majid to guide him across the Indian Ocean. On his return from India in 1499 he moored for a day off Unguja.
More Portuguese ships followed in the wake of da Covilhan and da Gama. They needed safe provisioning and repair bases for their voyages to and from the Far East, and so garrisons were established in the harbours of Unguja, Pemba and Mombasa.
Any early friendship was soon forgotten when the Portuguese took control of Unguja in 1503. A ship commanded by Rui Lorenco Ravasco moored off the southern end of the island while Portuguese sailors captured over 20 Swahili dhows and shot about 35 islanders. The Mwinyi Mkuu (king of Zanzibar) was forced to become a subject of Portugal, and agreed to allow Portuguese ships free access to Zanzibar. Additionally, he was required to pay an annual tribute to the Portuguese crown.
Portuguese domination of the region continued. In 1505 they took control of Mombasa, and in 1506 Pemba. Between 1507 and 1511 the Portuguese also occupied territories in the Arabian Gulf, including Muscat and the island of Hormuz.
By 1510 Unguja's tribute had fallen short and the people of Pemba had also become hostile to the Portuguese. Under Duarte de Lemos, the Portuguese looted and set fire to settlements on Unguja, then plundered the town of Pujini in Pemba. They soon regained both islands and by 1525 the whole east African coast, from Lamu to Sofala, was under Portuguese control. Gold, ivory, ebony and slaves from the interior were carried to Portuguese colonies in India or back to Portugal. Iron ore and garnets from Sofala, and coconut fibre and gum-copal (a tree resin) from the islands were also exported. Cloth, beads, porcelain and metal tools were imported to the east African coast from Oman and Portugal.
Around 1560 the Portuguese built a church and small trading settlement on a western peninsula of Unguja. This was to become Zanzibar Town. But although the Portuguese occupied Unguja, and forced the local people to trade under their supervision, the islanders continued to pay allegiance to the Mwinyi Mkuu, their own king.
Portugal was not the only European power with interests in the Indian Ocean. In November 1591 the Edward Bonaventura, captained by Sir James Lancaster, became the first English ship to call at Zanzibar. It was supplied with fresh food and water by the Mwinyi Mkuu. Soon, more European ships were calling at Zanzibar on their way to and from the Indian subcontinent and islands of the East Indies.
John Henderson, a Scottish sailor from one English ship, was reportedly held captive on Zanzibar in 1625. He later escaped, but not until he had fallen in love with a Zanzibari princess who escaped with him back to Scotland. Today, their portraits are in the collection of the Scottish National Portrait Gallery in Edinburgh.
With the advent of English ships in the Indian Ocean, the Portuguese needed to strengthen their position on the coast. In 1594 they built a fort at Chake Chake in Pemba, and from 1593 to 1595 Fort Jesus in Mombasa was constructed. Settlers arrived from Portugal, and a Portuguese garrison was established in Fort Jesus, brutally suppressing the local population. Mombasa became known as Mvita, 'the place of war', and the Portuguese governor as Afriti, 'the devil'.
Despite these fortifications, however, the Portuguese position in east Africa began to weaken. In Arabia, Hormuz was regained by the Persians in 1622, and in January 1650 Muscat was regained by the Omani Arabs. Following this victory, the Sultan of Oman's navy sailed to Zanzibar to help the Mwinyi Mkuu, Queen Mwana Mwema. The Omanis raided the Portuguese settlement on Unguja, killing many people and imprisoning about 400 in the church. They also attacked and burnt the Portuguese settlement on Pemba. By 1668, virtually the entire coastal area was in Omani hands. The only garrisons still held by the Portuguese were at Fort Jesus in Mombasa, and on the western peninsula of Unguja.
In 1682 the Portuguese persuaded the Queen of Pemba, who was living in Goa, to return, but this attempt to install a friendly ruler in Pemba was frustrated when her own subjects drove her out. The last Portuguese inhabitants were expelled in 1695.
By this time, Queen Mwana Mwema of Unguja had been succeeded by her son, Yusuf. After his death, towards the end of the 17th century, the island was divided between his two children, Bakari and Fatuma. King Bakari ruled the southern part of the island, with Kizimkazi as his capital, while his sister, Queen Fatuma, ruled the northern part. Fatuma supported the Portuguese, so her capital was built near the garrison on the western peninsula which later became the site of Zanzibar Town.
When the Omani fleet arrived at Mombasa and laid siege to Fort Jesus in March 1696, Queen Fatuma sent three dhows full of food to help the Portuguese defenders. The dhows were captured and burnt by the Omanis, who then attacked Zanzibar itself, forcing Queen Fatuma and her followers to flee into the interior of the island.
The siege of Mombasa lasted until December 1698, when the Omani forces took Fort Jesus and installed an Omani governor. Once again, the Omanis attacked Zanzibar. They drove out the last of the Portuguese settlers, captured Queen Fatuma and took her to Oman, where she spent the next 12 years in exile before returning to resume her rule. While she was away, her son Hassan took the title Mwinyi Mkuu, but paid allegiance to Oman.
Thus the Portuguese were finally ousted from the whole east African coast, and the Omanis were firmly in control of the entire region as far south as present-day Mozambique (which remained in Portuguese hands until 1972).