"The Middle Kingdom was a period of political and cultural unity following the political decentralization of the First Intermediate Period... It comprised the eleventh dynasty from the reunification of Upper and Lower Egypt under King Nebheptre Montuhotep II..." (Society and Death in Ancient Egypt: Mortuary Landscapes of the Middle Kingdom, Richards)The Eleventh Dynasty(2134B.C. - 1991 B.C.) began from about halfway through the First Intermediate Period and continued through the start of the Middle Kingdom. The pharaohs of the Eleventh Dynasty all reigned in the capital of Thebes. The pharaohs of the Eleventh Dynasty included Mentuhotep I,II, III, and IV, and Intef I,II, and III. After Mentuhotep II defeated the Heracleopolitans, his successors expanded and reinforced power over other countries, for example African neighbors and the Near East. The last ruler of the Eleventh Dynasty was King Mentuhotep IV. The death of Mentuhotep IV, and hence the end of the Eleventh Dynasty of ancient Egypt, is considered to be somewhat of a mystery; it is believed, in theory, that the king's vizier, Amenemhat, was part of the overthrowing of his kingship, and then leading to the beginning of the Twelfth Dynasty with King Amenemhat I(supposedly the actual vizier of Mentuhotep IV.)
The Twelfth Dynasty(1991 B.C. - 1784 B.C.) commenced with the reign of King Amenemhat I, who was questionably the vizier of Mentuhotep IV. Amenemhat obviously was involved in diplomacy and his military, as he led his armies south to the area of the Nile River, known as the Second Cataract, and with other regions he instituted political relations, establishing peace between Egypt and countries in Byblos and the Aegean Sea. Senusret I was born of Amenemhat, who arranged for Senusret to be his successor. Senusret I followed in his father's footsteps by expanding the empire as far as the Third Cataract, also he managed to maintain peace and unity within the Egyptian Empire and with other countries. Amenemhat II and Senusret II were also rulers in a time of contentedness during the Middle Kingdom. Other leaders of Egypt in the Twelfth Dynasty included Senusret III, who was a great pharaoh; he expanded the empire far into Nubia, built several fortresses throughout the country, held many campaigns and expeditions of which he was successful, structured villages and temples, built his pyramid in Dahshur, and documented his triumphs and success. Amenemhat III, who also built a pyramid at Dahshur, called the 'Black Pyramid,' was also a member of the Twelfth Dynasty, along with Amenemhat IV and Sobekneferu, the female ruler of the Twelfth Dynasty. Sobekneferu was the last ruler of the Twelfth Dynasty, as she didn't result any heirs, ending the dynasty of which she was a part of. The Capital of Egypt during the Twelfth Dynasty was located in Itjtawy.
The Thirteenth Dynasty(approximately 1782 B.C. - 1700 B.C.) is considered by some to be a part of the Second Intermediate Period, along with the Fourteenth - Seventeenth Dynasties, but is also portrayed by others to be a part of the Middle Kingdom. During this time documents and pharaohs aren't depicted clearly, as mostly only fragments and portions of historical documentation is found, of which pharaohs are mentioned vaguely. The pharaohs who reigned during the Fourteenth Dynasty seemed to have lost control and leadership over Egypt, as the decline sloped into the Second Intermediate Period when the Hyksos ruled Egypt.
"Unlike the First and Second Intermediate Periods, the Middle Kingdom... formed a political unity, the core of which comprised two political phases: the 11th Dynasty... and the 12th Dynasty centred in the region of Lisht in the Faiyum. Earlier historians considered that the 11th and 12th Dynasties marked the full extent of the Middle Kingdom, but more recent scholarship shows clearly that at least the first half of the so-called 13th Dynasty... belongs unequivocally to the Middle Kingdom." (The Oxford History of Ancient Egypt, Shaw)
During the Middle Kingdom, namely the Twelfth Dynasty, historians and writers recorded and documented the events and happenings of the Middle Kingdom. Of these individuals there was a priest who was a historian known as Manetho; he was responsible for a great amount of documentation of the Middle Kingdom, however, definitely not solely responsible. The controversy of co-regencies, a joint leadership of Egypt(for example a son is born of a king and he leads with his father until the time comes of the father's death), is present during the Middle Kingdom. The fall of the Middle Kingdom occurs as a result of the loss of leadership. The Middle Kingdom of Egypt was a remarkable era; it comprised of a time of peace, unity, and inner serenity.
Richards, Janet E. Society and Death in Ancient Egypt: Mortuary Landscapes of the Middle Kingdom. Cambridge, United Kingdom: Cambridge University Press, 2005.
Shaw, Ian. The Oxford History of Ancient Egypt. New York: Oxford University Press, 2000.
History of Egypt. InterCity Oz, Inc. 1996. September 29th, 2007. <http://www.touregypt.net/ehistory.htm#Old%20Kingdom>
Egypt in the Middle Kingdom. The Metropolitan Museum of Art. 2007. September 29th, 2007. <http://www.metmuseum.org/TOAH/HD/mking/hd_mking.htm>
Middle Kingdom. Jacques Kinnaer. 2007. September 29th, 2007. <http://www.ancient-egypt.org/index.html>
The Middle Kingdom. Richard Hines. 1996. September 29th, 2007. <http://www.wsu.edu/~dee/EGYPT/MIDDLE.HTM>
The Middle Kingdom of Egypt. Kelley L. Ross. 2006. September 29th, 2007. <http://www.friesian.com/notes/midking.htm>