The name of four of the 12th Dynasty pharaohs, under whom the Middle Kingdom of Egypt reached its peak of development, c 1938-1756 BC. The name meant "Amun is at the head". They include Amenemhet I (1938-1908 BC) (Sesostris I or Senwosret 1918-1875 BC) Amenemhet II (1876-1842 BC) (Sesostris II 1844-1837 BC) Amenemhet III (1818-1770 BC) (Sesostris III 1836-1818 BC) and Amenemhet IV (c 1770-1760 BC) (also Sebeknefru 1750-1756 BC the first attested female monarch).