Passage: The lack of formal authority was filled in the 1850s by a set of powerful merchant princes. In the east Muhammad Ahmad al-Aqqad controlled much land, but the most powerful was Al-Zubayr Rahma Mansur who came to control the Bahr el Ghazal and other parts of South Sudan. Al-Zubayr was a merchant from Khartoum, who hired his own private army and marched south.

Question: who controlled the land in the east?
Muhammad Ahmad al-Aqqad