Senuseret I (Part IV) and the Gold of Nubia.
Gold! Gold! Gold! The driver of empires and warfare since time immemorial. For the Egyptians, gold is a valuable resource to embellish temples and state projects. And Senuseret has a lot of these; you have to get your decorations from somewhere...
Into Nubia, the Eastern Desert and Sinai, Senuseret's soldiers and labourers are led in campaigns to find the precious resources needed to decorate the king's thirty-five different building projects in various parts of the Nile Valley.
Some of the major sites of this episode. (Wikipedia.org).
Negotiating the Second Cataract.
Nubian fortresses, from the JIAAW (Brown.edu).
Bibliography:
Wolfram Grajetzki. The Middle Kingdom of Ancient Egypt. 2006.