By 1811 traders from the East Coast were venturing into the interior of central Tanzania; by the 1820s they were on the southern plateau and soon traveling around the southern end of Lake Tanganyika. Coastal traders set up a base at Ujiji in 1831 that made it easier for caravans to penetrate areas beyond Lake Tanganyika. When they arrived in Buganda in 1844, they encountered for the first time a large, powerful state. Arab traders inserted themselves in the center of Nyamwezi country — and its politics — when they founded Tabora in 1852 in a locale that was already a hub of trade routes. Tabora served as a stopover for caravans going on to Ujiji or north to Buganda. Both Ujiji and Tabora are small urban centers in present-day Tanzania.

Caravans: Labor-Intensive, Expensive, and Risky
A caravan of human porters carrying goods over long distances was a labor-intensive, and therefore expensive, means of transportation. There were no roads or railroads. Draft animals were too susceptible to deadly tropical diseases such as sleeping sickness. Only a commodity such as ivory, commanding a very high price per pound, was worth the cost. Porters also carried imported goods (see Table 2 in Part 2: Zanzibar's Commercial Exports) and local products (iron hoes and salt). They trudged along, burdened with gear and supplies. Slaves walked to the coast, but only a few carried ivory. For porters and slaves, conditions were harsh, especially when food and medicine were running low. Tabora and Ujiji provided places to rest and take on supplies. Traders banded together for safety and for better deals when negotiating with local chiefs. A caravan might have a few hundred or even a thousand men. Mortality rates were high; two-thirds of a caravan cohort — traders, porters, camp-followers, slaves — might die before the journey was over. Raids, Theft, and Murder
Usually well-armed, caravans raided villages to take captives, to steal food, when villagers were unwilling to provide it, or to punish noncompliant chiefs. To obtain ivory they also seized captives for sale in the interior to people who were willing to pay in ivory to redeem their kin or to farmers needing extra labor. People were killed, homes burnt, in a pattern of violence that rippled forward (not unlike the "wave of violence" that Joseph C. Miller describes for the Angolan trade). People living along trade routes often constructed fortified villages. The frontier kept moving inland as elephant herds were depleted. Elephant hunters followed the frontier or began to raid for slaves. Farmers turned to producing food for caravans. Local chiefs, wherever possible, collected tolls from passing caravans. When caravans needed porters, chiefs were expected to help recruit them. The Arab Influence
Arab traders passed through the Nyamwezi heartland without paying any taxes under an agreement that Seyyid Said had worked out with a Nyamwezi chief. They diverted ivory that had previously flowed to the Nyamwezi. Tabora, with increasing numbers of East Coast traders and even Arab settlers, became a center of Arab influence. As Arabs meddled in local politics, Nyamwezi chiefs became divided into pro-Arab and anti-Arab factions. A chief who tried to contain Arab activities risked being ousted by a coalition of Arabs and other political enemies. Mirambo, an ambitious Nyamwezi chief, emerged as an anti-Arab leader in the 1860s. He organized the ruga-ruga — a motley band of displaced men, including war captives and escapees — and gave them enough firearms to seriously threaten the caravan trade. But Mirambo was not adverse to trade (that is how he obtained arms) so soon his capital was rivaling Tabora. In an intermittent war during the years 1871 to 1875, that seriously disrupted the ivory trade, he challenged a Tabora coalition of Arabs and Nyamwezi. When Sultan Barghash took the unprecedented step of sending a force from Zanzibar, it was no match for Mirambo. By 1881 Mirambo was controlling the route to Ujiji and to Buganda, which is not very surprising since he had thousands of guns — 20,000 firearms, according to a European visitor in 1883.

By the 1840s, both Nyamwezi and East Coast traders were operating west of the Western Rift Valley, beyond Lakes Tanganyika and Malawi, in territories that are now part of eastern Congo. In this region, two very ambitious men, who were fascinating characters, still widely remembered in central Africa, managed to carve out secondary empires largely because the profits of the ivory and slave trade gave them greater access to firearms and powder than any local leaders. Tippu Tip, son of an Arab trader and a Nyamwezi woman, moved to the upper Lualaba after trading from Tabora for many years. Since he controlled trade and dispatched well-armed raiding bands, he was soon a "Big Man" and very rich. He attracted local supporters by mediating disputes and providing security at the center of his territory. Tippu Tip was perhaps eastern Africa's most notorious slave-trader. However, his "empire" was politically underdeveloped, especially when compared to that of Msiri, who created a centralized state. Msiri, a Sumbwa from western Tanzania, settled south of Lake Mweru in the 1850s in a kingdom that was already a base for traders going farther west. The king, a Lunda, whose title was Kazembe, tolerated his presence until Msiri got involved in royal politics. After the king was killed in 1872 in a counterattack, Msiri controlled the copperbelt, but he did not call himself king until 1880, after his father had died in western Tanzania. For East Coast traders seeking ivory and copper, this was an important development. Opportunities for Some, Insecurities for Others, Tragedies for the Most Unfortunate
By mid-century, various combinations of the East Coast, Nile Valley, Red Sea, and Atlantic trading frontiers were converging in the African interior. Egyptian imperialism in Sudan had opened up a vast region to the ivory and slave trade — a frontier extending into the Central African Republic and northern Uganda — that was conducted by Khartoum-based traders. These "Khartoumers" were often ruthless raiders, causing great turmoil and suffering. From the Somali ports of Mogadishu and Brava, traders followed routes to northern Kenya or trekked into Ethiopia, making use of a network that linked the Red Sea and Indian Ocean systems. In central Africa, after Msiri made contact with Angolan traders, he sent caravans in two directions — to Benguela and Bagamoyo — selling ivory and copper to obtain guns and powder. Msiri's men were raiding as far as western Zambia. Thus, in 1876, when the East Coast slave trade was supposedly over, eastern Africa was teeming with Arab, Sudanese, Egyptian, Somali, Swahili, Nyamwezi, Sumbwa, and mixed-race "merchants" who continued raiding even as the demand for slaves at the coast was decreasing. There was a larger internal market for slaves, because slavery had become more widespread in eastern Africa during the nineteenth century; slavery persisted in some places until the turn of the century. Strong demand on the world market for ivory, copper, and other African goods helped to perpetuate networks of long-distance trade that now included, so typically, a raiding component. Thus the prosperity of the industrializing West and the tastes of its middle classes, continued to affect the security and lives of ordinary people across the eastern half of the subcontinent.

From the perspective of 1880, the impact on the interior was uneven in both its intensity and its timing. In some societies people had been procuring or producing goods for long-distance trade — or providing goods or services to sustain it, or trading to the East Coast — for decades or even a century. In other societies, only a few individuals participated, or involvement was seasonal or occasional. Responses and initiatives were diverse and changing. Patterns of trade shifted with the arrival of East Coast caravans, so that, for example, people who had been ivory traders such as the Kamba of Kenya, lost out to coastal competitors. For any particular people or subregion, the impact, if traced from about 1780 to 1880, might show dramatic changes. For example, the Yao, among the first to take caravans to coast, carried ivory and slaves, but rarely raided for slaves until after they had been attacked by well-armed neighbors who destroyed villages and took many captives. Yao chiefs responded by acquiring better rifles. Many Yao turned to raiding, so intensely from 1855 to 1885, that much land between Lake Malawi and Kilwa became depopulated.

Elsewhere, other lives and livelihoods were disrupted, other populations displaced, and other areas depopulated, all to varying degrees. Societies coped with demographic and ecological changes. Caravans spread diseases, such as smallpox. Both elephant hunting and raiding altered the environment. Without elephants, the mix of savanna grasses was different; farmland turned to bush if there were too few people to work it or it was too dangerous to do so. Pastoralists were less affected than farmers, even when trade routes passed near or through their territories. The frontier kept moving, yet in 1880 there were still remote societies outside its range.

Only a few societies, such as the Yao, Nyamwezi, Sumbwa, and Kamba, had opportunities to trade directly with the coast, and a cost-benefit analysis would not necessarily show a positive balance. The Nyamwezi, because their caravans were bare-bones operations, were especially resilient; they continued to trade at the coast even as duties on their ivory were rising. People in many societies benefited from expanding regional trade as producers, traders, or consumers of iron hoes, salt, livestock, grain, dried bananas, and pottery. Although the Ganda (of Buganda) sold ivory, bought guns, and raided their neighbors, even using canoes on Lake Victoria, there is also clear evidence for more intersocietal trade all around the Lake. The Gogo of central Tanzania sold ivory and bought slaves who labored to grow more food for passing caravans. While opportunities for wage labor were very limited, the hiring of porters eased the way for its later development. Many Nyamwezi were porters, hoping to save enough capital to enter the caravan trade.

The political impact could be positive, but more often it was mixed or negative, even contributing to the breakup of existing polities. The arms trade exacerbated internal conflicts — factions and succession wars — while the creation of standing armies or bands of enforcers, directly controlled by a king or chief, had the potential to build or strengthen centralized authority. Such forces sometimes included slaves. For Nyamwezi society as a whole society, the long-term cost of taking advantage of new opportunities was high because their success drew East Coast traders into the Nyamwezi heartland. The Shambaa kingdom of northeast Tanzania, between Mount Kilimanjaro and the coast, disintegrated in the 1870s when "it became profitable for local governors [seeking slaves] to both prey on their own subjects and to make war against their neighbors" (Feierman 1995: 367). Buganda, arguably the most powerful state in the upper Great Lakes, provides a rare counter example. Under the leadership of a savvy king, Mutesa I, the Ganda welcomed coastal traders and foreign visitors (e.g., Speke, Grant, Stanley) but also controlled their activities. Zanzibar maintained diplomatic contact with Buganda, and its traders were protected by the king. Most trade goods such as cloth, beads, and firearms were channeled through the court.

The impact of Zanzibar's commercial empire and its far-flung outliers, whereby eastern Africa was joined to the world economy, may be summed up in phrases that characterize the choices and dilemmas of people caught up in the process: opportunities for some, insecurities for others, tragedies for the most unfortunate. The insecurities and tragedies typically reflected the changing balance between the strong and the weak (Feierman 1995: 364).