Power ebbed from the Egyptian monarchy after a succession of weak kings. It is also possible that the nomarchs (governors of the nomes) and other vested interests compounded this by imposing a rotational system of succession to undermine centralized control. Consequently, the fortification and policing of northern and southern borders, which exemplified the 12th Dynasty, effectively collapsed. The first to crumble was Lower Egypt; weakened by plague and famine, it fell rapidly and without apparent resistance to the Semite Hyksos invaders. Ruling from Tell el Daba in the delta, they captured the ancient capital of Memphis. Meanwhile from the south, the resurgent kingdom of Kush annexed territory, and controlled the terms of trade, and the charging of levies, turning the tables on their former overlords. But, crucially, the rump Egypt did not collapse. The 17th Dynasty opened with a succession of rulers who, though limited in means, ultimately became architects of its revival.