South Sudan is located in the eastern region of Africa, bordering Sudan in the north, with a total area of about 619,000 square kilometers and a population of about 15.9 million. Sudan has a total area of about 1.88 million square kilometers and a population of about 49.5 million. South Sudan was once part of Sudan, but in 2011, South Sudan broke away from Sudan and became the 54th country on the African continent. So why did South Sudan leave its independence from Sudan?

First, race and religion are different. Sudan and South Sudan were originally the same country, but there were obvious differences in race and religion. The main ethnic group of Sudan is Arabs, accounting for about 70% of the total population of Sudan and believes in Islam. The three major ethnic groups in South Sudan are with Dinka people, Nuer people, and Shiruk people, all of whom belong to black people and believe in Christianity.
The reason for this difference is mainly due to historical reasons. Sudan is located in eastern Africa and borders Egypt in the north, and Egypt spans two continents of Asia and Africa, and has an important geographical location. Egypt has been a place where military strategists must fight in history. When Sudan is approaching Egypt, it is also affected by the expansion of major powers.

Ancient Egypt was the four ancient civilizations, but ancient Egyptian civilizations did not have a lineage. In 525 BC, the Achaemenid dynasty of Persia destroyed ancient Egypt and included Egypt in the Persian territory. After the rise of the Alexander Empire, Persia was destroyed and Egypt was annexed. After the death of Alexander the Great, Alexander's successor Ptolemy I controlled Egypt and founded the Ptolemy dynasty in Egypt.
In 30 BC, Rome destroyed the Ptolemaic dynasty in Egypt and turned Egypt into a province of Rome. In 395 AD, the Roman Empire designated Christianity as the state religion and banned other religions within Rome. As a province of Rome, Egypt also became a Christian area. The border between Sudan and Egypt was also affected by Egypt.

In the 6th century, Christianity was introduced to Sudan through Egypt and became the state religion of the Roman dynasty of the Sultan, and Sudan became a Christian region. But in the 7th century, the Arab Empire rose, and the core area of the Arabs was the Arab Peninsula. With the expansion of the Arab Empire, Egypt was incorporated into the territory. A large number of Arabs migrated to Egypt, and Egypt gradually became Islamized.
After the Arab Empire controlled Egypt, it continued to expand westward and southward, crossing the Strait of Gibraltar as far as the way, and expanding to Spain. During the heyday of the Arab Empire, it spanned three continents of Asia, Europe and Africa, with a land area of 13.4 million square kilometers. The Sudan in southern Egypt was naturally influenced by the Arab Empire.

After the Arab Empire controlled Egypt, it invaded Sudan along the Nile River. The Arab Empire controlled the northern part of Sudan, while the climate in southern Sudan was hot, and the Arabs were not adapted to the local climate and did not control South Sudan. During the Arab Empire's rule, the Arabs migrated to Sudan through Egypt and gradually became the main ethnic group in northern Sudan, and northern Sudan was also Islamized. Southern Sudan was not influenced by the Arab Empire and still believed in Christianity. This led to differences between the north and south of Sudan, where the north was mainly Arabs, who believed in Islam, and the south was black, who believed in Christianity.
Second, Britain's policy of division and governance. Britain was once the most powerful colonial empire in world history, and disputes around the world were somewhat related to Britain, and Sudan was no exception. In 1517, the Ottoman Empire conquered Egypt and turned it into a province of the Ottoman Empire.

In the 19th century, Ali, the governor of Egypt of the Ottoman Empire, led the Egyptian army to invade Sudan and incorporated the Sudan into the territory. Ali founded the Ali dynasty in Egypt and gradually broke away from the control of the Ottoman Empire. In 1882, Britain invaded Egypt and turned Egypt into a British protector.
After Britain controlled Egypt, it forced Egypt to sign the "Anti-Egypt Sudan Agreement". In name, the United Kingdom and Egypt jointly manage Sudan, but in fact, the United Kingdom completely controlled Sudan. Egypt dared not object to the policies formulated by the United Kingdom. According to the differences between north and south of Sudan, the UK adopted a policy of division and conquer, managing the northern and southern Sudan separately, and strictly prohibiting free exchanges between people from the north and the south. Under British rule, the gap between north and south of Sudan was further exacerbated.

In 1922, Britain recognized Egypt as an independent state, but continued to control Egypt's defense and diplomacy. It was not until 1952 that Egypt completely broke away from Britain's independence. In 1953, Britain gave Sudan autonomy and allowed Sudan to establish an autonomous government. In 1955, Britain planned to withdraw its troops from Sudan, but on the eve of Sudan's independence, South Sudan refused to form a country with Sudan.
In 1956, Sudan declared independence, and South Sudan refused to be a part of Sudan, and the first Sudan civil war broke out. The war lasted until 1972, when Sudan and South Sudan signed the Addis Ababa Agreement, granting South Sudan limited autonomy, and peace was temporarily reached between north and south of Sudan. But in 1983, Sudan decided to implement Islamic law across the country, which was protested by South Sudan, and the second Sudan civil war broke out.

The civil war lasted longer, reaching 22 years. It was not until 2005 that the north and the south signed the "Comprehensive Peace Agreement" to end the civil war. It can be said that after two long wars, both the north and the south were exhausted. According to the Comprehensive Peace Agreement signed by both sides, Sudan agreed to establish an independent country in South Sudan, but there will be a six-year transition period. In this way, in 2011, South Sudan declared independence from Sudan.