That video is not accurate.

From 1898-1956, Anglo-Egyptian Sudan was a single territory that encompasses the territories of the present day Republic of Sudan, and Republic of South Sudan. There was not a time when the north and south were separate British colonies.

Also, technically, Anglo-Egyptian Sudan was not a British colony but was instead a condominium. That is, it was legally considered territory under the joint authority of Britain and Egypt under the terms of the [Sudan Convention of 1899](https://en.wikisource.org/wiki/Sudan_Convention_(1899)). It is important to note that in 1899, Egypt itself was a protectorate of Great Britain. So, at first blush the arrangement for Britain and a colony to share authority over another colony seems unusual. However, a few historical events explain the British reasons for entering into this unusual arrangement.

• From 1822-1882, the territory that would become Sudan had been conquered and ruled by Egypt under Muhamad Ali Pasha and his successors.

• In 1882 a rebellion against Egyptian imperial rule and harsh taxation flared up under the charismatic Sudanese religious leader Muhammad Ahmad, driving Egyptian armies out of Sudan. He was declared the Mahdi by his followers, and his successful rebellion established a new islamic polity in the region known as the Mahdist state or the Mahdiyya.

• The Mahdiyya persisted for more than 15 years, in continual conflict with Egypt. However, in 1892, Britain grew wary of the expansion of French territories in Central Africa and the expansion of Leopold's Congo Free State. Britain determined that it would be wise to support a combined British-Egyptian force to conquer the Mahdist state and reiterate Egyptian claims to the territory, to before French or Belgian (or Italian!) forces could claim the territory.

• After Anglo-Egyptian forces reconquered the Sudan, Britain "suggested" the condominium arrangement in consideration to the shared contributions of the Anglo-Egyptian army in the reconquest.

So, all of this is to say that the condominium arrangement was a way of keeping rival powers out by pressing old Egyptian claims and presenting the territory as "land in rebellion". As I will explain below, this "condominium" was a diplomatic fiction, and Britain demonstrated that they were the dominant power in the partnership.

Under the terms of the Sudan Convention, the staffing of administration in A-E Sudan was meant to be decided in collaboration. London would nominate a candidate for Governor, and Cairo would confirm the candidate.

In practice, the relative positions of the two countries as great power and protectorate meant that Egypt always confirmed British nominees, and from 1899-1956 every governor was British. Similarly, the district officers who were the closest subordinates to the governor also came from Britain. It was only at the lower levels of the administration, at the village and sub-district level that you started seeing Egyptian administrators.

Of course, the arrangement described above only really applied to the northern, muslim, arab region of the Sudan. In the south, Britain took an even more hands-on posture. Since the peoples of the south had not been converted to Islam to any great degree, Britain encouraged christian missionary activity in the region. While Arabic was used as an official language in the muslim north, mission schools encouraged the use of English as an official language in the south.

So, if we circle back to the claim from the youtube video, it is fair to say that Britain administered the north and the south as though they were two separate colonies, and after 1924 Britain tried to encourage separate trajectories for the north and the south.

So, to the next logical question: Why didn't Britain just divide them into separate colonies then?

Firstly, despite the fact that Egypt had been sidelined in the administration of the colony, Egypt and Egyptians continued to have interest in Sudan, and desired to have a say over Sudanese affairs.

Also, the relationship between Egypt and Britain changed. In 1922, Egypt gained independence from British protectorate, except for the Suez canal zone.

So, any effort to split off the southern Sudan into a separate colony (presumably British-controlled) could reasonably be expected to be received poorly in Egypt and excite Egyptian nationalist passions. Given the proximity of the strategically and economically important Suez canal, causing furor among the Egyptian population would seem a bad idea.

Skipping ahead, by 1952 the relationship between Egypt and Britain again changed with the overthrow of the Egyptian monarchy and the rise of Gamal Abdel Nasser, and his pan-arabic ideology. President Nasser's decision to nationalize the Suez canal in 1955 resulted in British-French-Israeli combined effort to seize the canal by force, and dramatically worsened Anglo-Egyptian relations. In 1955 Nasser also announced the abrogation of the Sudan Convention of 1899 as well as the Anglo-Egyptian treaty of 1924.

Shifting our focus back to Sudan, political cultures had grown out of university student bodies in the 1940s and 1950s. By 1955 there were two broad political blocks in the north. There were those who preferred the dissolution of the Anglo-Egyptian condominium arrangement in favor of Egyptian-Sudanese unity, united under the rallying cry of "Unity of the peoples of the Nile". Opposing them were those who preferred continuing the existing colonial economic development program (implying a grudging acceptance of British rule), whose rallying cry was "Sudan for the Sudanese". Then of course, there were the separate interests of the southern Sudanese.

Britain, faced with Egyptian abrogation of the treaty that served as the diplomatic basis for the Anglo-Egyptian Sudan, and a mass-political movement that favored Sudan-Egypt unification, entered negotiations with Egypt with the goal of avoiding unification.

So, in this climate, Britain concluded that British diplomatic interests were best served by ignoring southern Sudanese interests, and working with the "Sudan for the Sudanese" political bloc in the north to try and achieve Sudanese independence without unification with Egypt.

With this in mind, had Britain attempted to separate southern Sudan from the rest in the late 1940s or early 1950s, a plausible outcome would be exciting pan-arab furor in Egypt and among Sudanese unionists. The "sudan for the sudanese" bloc did not favor southern separation, so pursuing that course of action would drive away potential allies, and increase the risk of driving the whole region into Egyptian influence. From the British perspective, changing the rules and splitting off the south as a separate colony was not worth the potential blowback.