The Gambella post later gained great importance and became an important commercial center for importing coffee and helped develop commercial transport via Nile steamers. The British also exploited it to monitor the situation in South Sudan, especially the Nuer tribe, during their violent revolution against the British, which continued intermittently between 1901. It also played a major role during World War II when Italy occupied Abyssinia, and it remained under British rule of Sudan. In addition to its role in resolving problems and following up on various issues in that region, which was characterized by a great deal of instability.

In the rest of the border, the situation was similar: disagreements and disputes stemming mainly from the errors that accompanied the demarcation of the borders; as in the Karmak post, where the exchange of slaves continued in that region until 1929 despite the great efforts made by the British in Sudan to combat it. However, the slave trade flourished until the late twenties. One of the common tribal problems with Abyssinia in the late twenties led to...

It was one of three problems that disturbed the peace of the British rulers of Sudan, adding that the border between Sudan and Abyssinia was a fertile ground for troublemakers from the people of Beni Shangul.

In 1925, the British Prime Minister Ramsay MacDonald raised the border issues between Ethiopia and the British colonies in Sudan, Somalia, and Kenya with Crown Prince Ras Tafari during his visit to London. Ras Tafari replied that the cause of the problem was the lack of border markers on the ground.

In 1927, the British authorities uncovered a large network for smuggling and selling slaves from Abyssinia to Sudan. The network was led by Sheikh Khogli Al-Hassan, one of the sheikhs of Beni Shangul, who used to send slaves to one of his wives who resided in Karmak, from where they were distributed and sold to the regions of the White Nile, Kordofan, and Darfur. Hundreds of cases were seized, and "Set Amina," Khogli Al-Hassan's wife, was prosecuted.