The Sun disc itself, first as a heavenly body, later personified as RA
The word ‘aten’ itself means any round objects The ‘aten’ together with the concept of divinity appeared the first time
2000 B.C., ,where the king Amenemhat I is said to soar into the sky uniting with Aten, his creator. The word ‘aten’ later appears together with a symbol of a deity who is carrying a sun disc on his head, on an inscription of Thutmose at Tombos in Nubia, ca 1500 B.C. Later, in the 16th century B.C. the ruler Amenhotep I is likewize after his death ‘united with the one from whom he had come’. From there the step to elevating the ‘aten’ to a deity in its own right isn´t all that far.
The earliest depiction of the ‘aten’ as Aten can be found on a monument dedicated to Amenhotep II at Giza. Here we can see the winged sun disc embracing the royal cartouche with its outstretched arms. During the rule of Thutmose IV the Aten is said to be in the vanguard of the army, which place was usually occupied by Amun.
Next we find that Amenhotep III most likely had a temple to Aten constructed and a priesthood installed at Heliopolis. Further, he held courtiers with titles like Hatiay, ‘scribe of the two granaries of the Temple of Aten in Men-Nefer (Memphis)’. Also the palace of Amenhotep at Malkata bore the name ‘Splendour of Aten’ and ‘Per Hay’ (home of rejoicing).
During the Amarna period, under the reign of Akhenaten (Amenhotep IV) the sundisc, as a heavenly body, was exalted to be the only god in existence, something which had been unheard in Egyptian religion, and which undoubtedly caused much consternation among the priesthood. Aten was then depicted as a sundisc with rays ending in life-giving hands.
During the first years of his reign, Akhenaten kept the capital at Waset (Thebes). He even had a temple to Aten constructed outside of the eastern wall to the great temple to Amun. This was torn down after his reign by Horemheb and some 35.000 blocks went into the pylon IX at Karnak. This temple was called Per Aten (house of Aten)and included at least three sanctuaries, where one of them was called the ‘mansion of Bn-ben’, thereby linking to the Primeval Mound on which the sun god appeared to create the world in the sun cult at Heliopolis.
In the 6th year of his reign, Akhenaten founded the city of ‘Akhet-Aten’ (‘Horizon of Aten’), despite the grumblings of a priesthood rendered powerless. This is the modern site of el-Amarna. This is also the time when the king changes his name from Amenhotep (Amen is content) to Akhenaten (Beneficial to Aten) and assumes a new royal titulary, from which can be understood that Re is absorbed into and the same as Aten, and therefore it can be said to be a renewal of kingship as it was over a thousand eyars earlier in Dyn V.
But this period was brief, only ca 15 years, and may in fact not have had any large effect outside of the royal court. For people in general, life probably went on as it had always done, they kept on praying to their same local deities and was largely unaffected by the changes on the national level. After Akhenaten´s death the priesthood of AMUN reinstalled the old religious practice, tore down the temples to Aten and the Amarna period became an exception in the history of Ancient Egypt.