.Kinglists refer to his king as Nebka, others as Sanakhte and there is some question as to whether these are the same person or not. It may be that Nebka founded the dynasty and Sanakhte ruled later, perhaps after Khaba.

One theory holds that Djoser and his mother were already in power when Khasekhemwy died, so he may have usurped the throne from the rightful ruler (Djoser, either his father or brother). Most other egyptologists feel that he is a later king, between Djoser and Huni. His position in the chronology is problematic, as the horus-name Sanakhte cannot be assigned to any of the kings in the king list.  However, it has been suggested that this is a horus-name for the king Nebka, who is only known in the king lists.

The Turin king list and Manetho show the succession as:
Nebka
Netjerikhet (Djoser)

The papyrus Westcar is different:
Netjerikhet (Djoser)
Nebka
Huni

Others do not mention Nebka at all, including the writings of the Egyptians themselves. The archeological sources show that Nebka should be placed between Djoser and Huni, asserting that the Turin king list misplaced him (assuming you believe that Sanakhte and Nebka are the same king). Tradition holds that he was the founder of the dynasty and the older brother of Djoser, but this has been questioned lately.

Traditionally, Nebka/Sanakhte was considered the founder of the third dynasty, but this has been questioned, since nothing is known of his reign. His tomb has not been identified with any certainty, although the remains found in a mastaba tomb from Beit Kallahf near Abydos match Manetho's description of a tall, heavily built ruler; there is some speculation that this may be his final resting place. No funerary monument (pyramid or temple) has been found.

The name Sanakht has been found in the remain of a small pyramid built on Elephantine (which was the southern border of Egypt at the time --the country was much smaller than we are used to). He is shown smiting a foe, a common "kingly" pose, on a fragment of relief found int eh Sinai, as well.

pharaohs

Nebkha
Djoser
Sekhemkhet
Khaba
Huni

monuments

Mastaba tomb
Pyramid at Elephantine