Zanzibar's economy is dominated by agriculture, rich in cloves and coconuts, known as Lilac Island, with 4.5 million lilac trees, accounting for more than 70% of the world's supply, most of which are produced on Pemba Island. There are more than 5 million coconut palms, most of which are concentrated in Zanzibar. In addition, it also produces rice, cassava, sugar cane, fruits, etc. Zanzibar has no industry today, and since the end of the slave trade, Zanzibar has relied entirely on the clove trade and the supply of merchant ships to and from it.

In 1828, the German chemist F. WÖ Hler, 1800-1882) was the first in the world to synthesize urea artificially. According to the "vitality theory" that was popular in the chemical circles at that time, urea and other organic substances contained a certain vitality and could not be artificially synthesized. Wüler's research breaks down the absolute boundaries between inorganic and organic matter. However, at that time, the use of urea as a fertilizer was not yet recognized.

In 1838, the English squire L.B. Ross treated phosphate rock with sulfuric acid to make phosphate fertilizer, which became the world's first chemical fertilizer.

In 1840, the German chemist J. Vonliebig (1803-1873) published the book "The Application of Chemistry in Agriculture and Physiology", which established the theory of plant mineral nutrition and the theory of replacement, completely repudiated the two major theories of plant nutrition of "humus" and "vitality" that were prevalent at that time, and laid a theoretical foundation for the invention and application of chemical fertilizers. Liebig also invented potash in 1850.

And in 1845, Liebig, who had been "kidnapped" from Hesse-Darmstadt (Duchy of Hesse) by the Research Institute of the Faculty of Agriculture of the Imperial University, invented potash five years ahead of schedule, which greatly increased the agricultural output of the Empire.

Zanzibar is dominated by agriculture, and there is a market for fertilizers here. Li Jie, who runs a fertilizer company, set up a production plant in Fu'an, eastern Mindong, after obtaining a production license from the research institute, and today he is carrying the phosphate and potassium fertilizer produced by his factory to Zanzibar on a papaboard merchant ship that he has just bought from the Mawei shipyard, where he is ready to sell it.

At the docks in Zanzibar, Li Kit and his assistant and translated cousin charter took matters at the Imperial Chinese Consulate at the docks, and then they prepared to go to the local plantations to market their products.

In the streets, however, trouble arose, and Qaboos ibn Sa'id was the son of Sa'id ibn Sultan, the king of Oman (then known as the Muscat Sultanate), and as the son of the king, like the sons of the powerful, he was uneducated and cruel. Today he saw two men in a western suit on the street in Zanzibar, which is also very popular in Oman, and it was not related to it, but on the street Qaboos bin Said and his entourage were angry that they had kicked and beaten a civilian.

"You pariah, you dare to steal my money, you don't want to live! Call me. "Probably a poor Arab child, maybe he was controlled by a human trafficking organization and reluctantly embarked on the road of theft, but poor he thought that he could get something from this gorgeously dressed boy, and now he was pressed on the street to vent his anger.

Li Jie really can't stand it, even if he is a thief, but he is still a child, in the domestic emperor's teaching, "children are the future of the motherland", the country will give every child the best environment, when the charter was just about to hold him, Li Jie rushed up with an arrow, grabbed Qaboos, pushed away his entourage and scolded loudly: "What are you doing? Even if he is a thief, he should be handed over to your officials, what right do you have to beat people indiscriminately, he is still a child, do you have humanity. ”

Seeing a yellow man actually dare to drag himself, Qaboos felt very angry, as the prince of Oman, in his opinion, if it were those white people, he would be afraid, for this thin yellow man actually dared to drag him, making him feel that his dignity was insulted, Li Jie said a Chinese language, although he couldn't understand it, but he didn't care, Qaboos grabbed Li Jie's clothes and punched him, under the leadership of the master, those servants also rushed forward to beat Li Jie, and when the charter saw that the situation was wrong, he immediately ran to the consulate for help.

Later, under the leadership of the military attache of the consulate, Li Jie was carried back from the street, and Qaboos bin Said was also detained by the consulate, looking at Li Jie who was dying, Chen Shu, the consul in Zanzibar, immediately realized that the opportunity for the governor of East Africa and others had come, and he immediately asked people to send a message to the governor's palace in Mogadishu. At this time, Zheng Qi was not in Mogadishu, he was planning the southern section of the East African Railway with Li Hongzhang in Lamu, and after receiving the news, he and Li Hongzhang realized that the opportunity had come.

On October 13, 1848, Zheng Qi, the Governor of East Africa, lodged a diplomatic protest in the name of the African Administrator of the Chinese Empire to the Sultanate of Muscat, that is, the State of Oman, hoping that the Sultanate of Muscat would give an explanation for the beating and humiliation of citizens of the Chinese Empire in Zanzibar and hand over the murderers.

Along with the protest to Zanzibar, there is also a gunboat under the East African Fleet of the Indian Ocean Navy, although the East African Fleet at this time is not equipped with the main ironclad ships of the Xia class, but there are the latest all-steel gunboats produced by the Empire, this type of gunboats are all riveted with steel, at this time electric welding has not yet been invented, and the hull of the warship is mostly connected with rivets. This type of gunboat was named the "Mosquito" class, which meant that even if the ship was small, a bite would make you bleed. Although its displacement is only about 900 tons, it has one 120mm main gun and six 75mm secondary guns in the front and rear.

In the face of such a warship, even if it is only a gunboat, the Omani king Ibn Sultan Saeed has to feel tricky, after all, this matter is not easy to solve, Qaboos bin Saeed is his son he must not hand over, and now there is a tendency to divide the country (by the middle of the 19th century, the Oman region has formed the Muscat Sultanate, the Omani Imam and the Omani coastal emirates, namely "Trusil Oman", and later became the United Arab Emirates), what to do, what to do! In the end, he could only find the British, hoping that they would help him.

Finally, the three countries began negotiations in Stone Town, Zanzibar.

The Chinese Empire demanded that the Sultanate of Muscat hand over the murderer, apologize and compensate the victims with 100,000 Chinese dollars, and lease Pemba Island to the Chinese Empire for a period of 99 years. To protect the security of the citizens of the empire in Oman, Zheng Qi also demanded the rights of concessions, consular jurisdiction, and customs reconciliation in Oman itself.

In the face of such harsh and humiliating conditions, Oman will certainly not agree, and Britain will not let China obtain so many benefits in Zanzibar, after all, Oman is the biggest beneficiary of Britain's relevant interests, the colonial government of Cape Town has refuted many unreasonable demands of China, and the negotiations have reached an impasse, China refuses to make concessions and concessions on the issue of concessions and privileges, and Britain resolutely does not allow China to obtain concessions or military bases in Zanzibar.

But in the following month, Zheng Qi personally went to Stone Town, Zheng Qi received news from Jinyiwei that the British were also interested in Zanzibar, and even supported some chiefs in Oman mainland (the Arabian Peninsula) to divide the Muscat Sultanate.

The next day, the attitude of the British turned 180 degrees, and Ibn Sultan Sa'id knew that the British had been bought by the Chinese and that his kingdom was finished.

On November 9, 1848, the Chinese Empire and the Sultanate of Muscat signed the Treaty of Stone Town, under which the Chinese Empire obtained Pemba Island as a concession for 99 years, in addition to a series of open door rights such as consular jurisdiction and tariff coordination. Although the treaty was far from what was expected, and did not acquire the island of Zanzibar, it also achieved its basic strategic objectives.

In addition, Zheng Qi, on behalf of the imperial government, secretly signed a "Zanzibar Secret Treaty" with the colonial government of Cape Town, in which the Chinese empire allowed Britain to include Zanzibar in the protectorate, while the British recognized Pemba Island as the Chinese empire, and the Muscat Sultanate or its secession states had no right to claim sovereignty over the island.

When this treaty reached China, Lin Hong and his cabinet were basically satisfied with the treaty, and with Pemba Island, there was a bridgehead to South Africa, which was even more powerful for the conquest of the Zulu region