In his sixth year, he re-dredged an Old Kingdom canal around the First Cataract to facilitate travel to Upper Nubia. He used this to launch a series of brutal campaigns in Nubia in his sixth, eighth, tenth, and sixteenth years. After his victories, Senusret built a series of massive forts throughout the country to establish the formal boundary between Egyptian conquests and unconquered Nubia at Semna.[34] The personnel of these forts were charged to send frequent reports to the capital on the movements and activities of the local Medjay natives, some of which survive, revealing how tightly the Egyptians intended to control the southern border.[35] Medjay were not allowed north of the border by ship, nor could they enter by land with their flocks, but they were permitted to travel to local forts in order to trade.[36] After this, Senusret sent one more campaign in his 19th year, but turned back due to abnormally low Nile levels, which endangered his ships.[34] One of Senusret's soldiers also records a campaign into Palestine, perhaps against Shechem, the only reference to a military campaign against a location in Palestine from the entirety of Middle Kingdom literature.[37]