Key dates (approximate)

• 1620s: Rise of the Ya'rubi dynasty
• 1650s: Ya'ariba expel the Portuguese from Muscat and raid their holdings in East Africa
• 1720s: Ya'rubi rule implodes due to internal squabbling, sparking a civil war in Oman
• 1740s: Rise of the Al-Busa'idis
• 1770s: Al-Busa'idis establish themselves as sultans in Oman and Zanzibar
• 1832: Al-Busa'idi Sultanate takes Mombasa from the Al-Mazru'is
• 1843: Capital of the Sultanate of Muscat and Zanzibar is shifted to Zanzibar
• 1856: Sa'id bin Sultan Al-Busa'idi dies while at sea
• 1861: Canning Award divides Omani Empire into two domains, in Muscat and Zanzibar
• 1890: Establishment of British Protectorate in Zanzibar
• 1964: Zanzibar becomes part of Tanzania

The Ya'ariba and the Omani Empire

Although Oman has always maintained a presence in the Indian Ocean, the history of Omani political expansion becomes clearer in the early 1600s with the establishment of the Ya'rubi Imamate in Oman. By 1623, with the fortunes of the Portuguese in the Indian Ocean in decline, the tribes of Oman united under an Imamate headed by Nasser bin Murshid Al-Ya'rubi. Over the course of the 1640s, the Omanis scored a series of decisive victories against the Portuguese on land and were able to establish themselves at the port of Suhar (Sohar).  This momentum continued over the 1640s, and by the beginning of 1650, the Ya'rubis had expelled the Portuguese from Muscat.

After taking control of Muscat in 1650, the Omanis shifted to an offensive approach, attacking Portuguese holdings across the Indian Ocean. The Ya'rubi dynasty seemed to prefer an ad-hoc series of raids on the Persian, Indian, and East African coasts that resulted in different forms of Omani hegemony. They sacked Zanzibar in 1652, raided Mombasa in 1661, attacked Diu in 1668, sacked Mozambique in 1671, plundered Bassein in 1674, and pillaged and destroyed the Portuguese factory at Kong in 1684. From Mombasa, they sought wealth from East Africa – particularly from the island of Pemba and from Kilwa, which gave them access to the hinterland. From Mombasa, the Ya'rubis exercised suzerainty over a strip of coastal fortifications that ran south to Kilwa. Their associates from Oman, the Mazru'is, were eventually installed as governors of Mombasa during the early 1700s, and would send annual payments to Oman.

Ya'rubi rule over Oman and East Africa would not last long. In 1719, the Ya'rubi Imam Sultan bin Saif II passed away. His death brought about a struggle between different tribal and religious leaders in Oman, each of whom had rallied behind different political contenders. As tensions grew, the country descended into civil war, with rival alliances of tribes (grouped into two, the Hinawis and the Ghafiris) each backing different candidates to the imamate.

The Al Busa'idi Dynasty

It was within this context that a new leader emerged: Ahmed bin Sa'id Al Busa'idi, a successful coffee merchant and the Ya'rubi governor of Suhar. When the rival claimants to the Ya'rubi Imamate had all died, he was in a clear position to launch a bid for power, in which he succeeded. Over the course of the last quarter of the 1700s, Ahmed bin Sa'id and his son Sultan set about reassembling the older Ya'rubi holdings around the Persian Gulf and East Africa. The Al Busa'idis were at times able to compel smaller shaikhdoms in the region to pay them nominal tribute, but were rarely ever able to exercise real power over them.

The sultans then turned their attention to East Africa, and were able to quickly establish themselves in Zanzibar; from there, they looked to the East African coast as a frontier of expansion. However, instead of a heavy military presence, they mostly preferred to keep prior political arrangements with local authorities in place, asking only that the chiefs give up the right to collect customs in exchange for Al Busa'idi protection. They would then hand over the customs administration to their Indian customs master's firm, who would then disburse regular payments to the local chiefs and their retinues. The various ports of the Omani empire each had their own customs master. In general, the customs masters themselves were generally Gujaratis from Kachhch. Two of the larger customs firms were Jairam Shivji and Ladha Damji. Customs firms kept the names of the founder even after their death.

The success that the Al Busa'idi sultans saw was in part due to their mercantile inclinations. Theirs was a vision of wealth built on trade: they engaged in reciprocal trade agreements with various rulers in India and European empires around the Indian Ocean, lowering customs duties and easing the transit of goods between the East African coast, Mauritius, Madagascar, Muscat, India, and Persia. They also brought different ports into the imperial regime without force: they leased the Persian port of Bandar 'Abbas and its environs from the ruler of Persia in 1780, they established themselves as suzerains in Gwadar, on the coast of Baluchistan, a few years later. In each of the ports they incorporated into the Omani empire, they appointed a customs master – usually a Gujarati Indian, Hindu or Muslim, who would be responsible for collecting duties on behalf of the sultan.  If the Busa'idis built their empire on trade, these Indians held the empire's purse-strings.

However, the bulk of Al Busa'idi success in empire-making came from their diplomatic tactics. In addition to inking trade agreements with the French, the Americans, and the Germans (among others), the Al Busa'idi sultans gradually aligned themselves with the British East India Company – and later, the government of British India. Sa'id bin Sultan Al Busa'idi – Sayyid Sa'id, as many called him – was perhaps the most adept at building these sorts of alliances, and is indeed most associated by scholars with the success of the Omani Empire. By virtue of his diplomatic engagements with various foreign states – especially his eventual alignment with the British – Sayyid Sa'id was able to consolidate Oman's power over the Indian Ocean basin.

The sultan, who spent his years shuttling back and forth between Muscat and Zanzibar, died at sea in 1856. His death caused some concern among the political elites of Arabia and East Africa, as well as in diplomatic circles in Bombay: he did not leave a will, nor did he designate a clear heir to his far-flung empire. The matter of the future of Sa'id's dominions was referred to a committee headed by the viceroy of India, Lord Canning, who in 1861 split them into two separate domains: an East African one centered at Zanzibar headed by Sa'id's son Majid, and an Omani one anchored in Muscat ruled by his son Thuwaini. As far as historians are concerned, the Canning Award (http://legal.un.org/riaa/cases/vol_XXVIII/107-114.pdf) dealt the deathblow to the Omani Empire: it created two independent sultanates, both of which ultimately fell under British protection, and signaled the decline of two centuries of Omani hegemony in the Western Indian Ocean.

Waraqas and the Omani World of the Indian Ocean

Beyond illuminating the economic structures of the Omani Empire, these waraqas act as a lens to understanding the multi-dimensional Omani world of the Indian Ocean. These debt records move us away from a narrative of sultans and soldiers. Instead, they conceptualize a world in which ordinary Arab and Swahili actors in Oman and East Africa linked ports together through their physical movements between them, but also through the circulation of commodities, capital, and ideas between the ports of South Arabia and East Africa. Through these actions, they forged more durable links – ones that last, in different forms, to this very day.

Seen through the waraqas, what emerges is a vibrant world of migration and exchange that outlasted political changes and linked together port cities and hinterlands into a durable commercial sphere. The circulation of money, property, and people continued well after the division of the Omani Empire, forging ever-stronger links between Oman and East Africa deep into the twentieth century.

Perhaps the most important series of events motivating these circulations were the commercial booms that swept the East African coast during the nineteenth century. During the first half of the nineteenth century, the region witnessed a massive expansion of the ivory trade - due in large part to increased European demand for ivory. Although East African merchants had been exporting ivory to India and China for centuries, the emergence of England as a market for ivory injected it with a new sense of enthusiasm. By the middle of the nineteenth century, merchants witnessed the development of an international commodity chain between the interior of East Africa, the productive hinterland; Zanzibar, the regional ivory entrepôt; Bombay, the processing station; and markets in London, Marseilles, and Hamburg. The advent of an American mercantile presence in Zanzibar, and the infusion of American cloth into the market, further stimulated mercantile expansion into the interior of East Africa.

Alongside the expansion of the market for ivory, the region's merchants also witnessed a tremendous (and much longer-lasting) growth in demand for cloves. Available figures show that while clove exports were low during the early 1800s, they enjoyed an enormous boom during the middle of the century. Even two decades after the first clove trees were introduced to Zanzibar sometime around 1819, most clove plantations belonged to the sultan; it was only during the 1840s that many Indian merchants began to invest capital in clove plantations, giving rise to a clove-growing bonanza in Zanzibar. By the second half of the nineteenth century, Zanzibar and Pemba accounted for the bulk of cloves produced worldwide.

As the settlement of Zanzibar and the East African interior expanded, so too did plantations along the East African coast, many of which were dedicated to growing the foodstuffs and grains that would supply local markets. Omani planters with land along the coast grew rice, millet, sorghum, and sesame, alongside crops that were more explicitly earmarked for international export. Long-settled Arabs and new arrivals alike could thus establish themselves as landowners and entrepreneurs in East Africa.

The ivory boom, however, did more than just fuel the growth of a plantation society on the East African coast. Through successive generations of ivory traders, Omani merchants were able to establish themselves in key towns in the interior of East Africa. The town of Tabora, a principal ivory trading station in the interior, was almost wholly populated by Arabs of Omani descent, who chose to stay in the interior rather than return to the coast, carving for themselves positions as middlemen in the ivory trade. Others established plantations in the interior rather than the coast, reaching as far upcountry as the Congo.

The commercial bonanza was not limited to East Africa: by the second half of the nineteenth century, merchants in the Gulf were reaping the rewards of the transformations that had taken place around the Western Indian Ocean. Historians have outlined how the market for dates expanded in important ways during the 1880s, reaching consumers in Europe and America. Between 1899 and 1906, the earliest years for which there are published figures, Muscat's date exports nearly doubled, and Omani dates were regularly being consumed in households in the United States.

In both Oman and East Africa, the work of financing Omani political and commercial expansion largely fell to the region's Indian merchants. Merchant houses from Kachchh, in Gujarat, featured prominently as customs masters throughout the empire, from Bandar 'Abbas to Zanzibar and beyond. Indian merchant communities in Oman and East Africa bankrolled Omani military campaigns, loaned money to the sultan and his family, and provided all manner of public finance more generally. They also constituted the principal source of commercial and agricultural credit more generally, throughout South Arabia and East Africa, loaning out money to prospective ivory caravan leaders, planters, and other commercial aspirants. Their role was neither small nor temporary; they constituted a core feature of the Omani world of the Indian Ocean, and their presence in both South Arabia and East Africa is highly visible even today.

This is the world that the waraqas emerged from: one in which a growing world of commerce offered up opportunities for Arabs, Indians, and Swahili economic actors, and in which Western India, South Arabia, and East Africa became intertwined with one another in a way that politics alone could not capture. As the waraqas themselves tell us, the emergence of a plantation economy on the East Coast of Africa (and the later boom in Oman) was not simply an economic phenomenon: it was a social one as well, and one that firmly linked the fates of Oman and East Africa together. For as the plantation economy and ivory trade took off in East Africa, hundreds of Omanis began migrating there in search of economic opportunities, pawning what land they had in Oman to finance a new life across the ocean.