"Atlantis" in Greek means literally "That pertaining to Atlas." Some criticism of Plato has aserted there is no Egyptian deity analogous to Atlas. That is incorrect, the proper analogue is Shu, the god that holds the sky up.
In Egyptian mythology, the sky (Nut) and Earth (Geb) are lovers. The older hidden meaning is that Atlantis is the place where heaven and earth meet or where the lovers come together. In Plato's retelling, the lovers are specifically Poseidon and Cleito and the place is what would become Atlantis' capitol city (Evidently also called Atlantis by Plato)
The place where Poseidon and Cleito came together was later made into a temple. The situation is exactly as in Babylonian pyramid-temples or ziggurats, where the king would perform ritual Sacred Marriages with a Priestess, each one of them seen as embodying a deity. In Sumeria and later Babylon, memorial plaques were left at the temple after the Blessed Event.
Below, Lovers and the fruit of their union, from Catal Huyuk
Prehistoric sculpture depicting the Lovers at the very beginning of the Neolithic, in Israel (Naftufian). Similar sculptures are found rarely in the Shara and in CroMagnon Europe.
The Babylonian Lovers in their memorial plaque, some time later than the Sumerian version before.
In the Atlantis story of Plato, Poseidon stands for the Egyptian Nun, the God of the Waters and Father of the Gods. This is another incorporation where we can pinpoint the original Egyptian myths exactly: this is an early origin story where the Eight gods of the Ogdoad emerged at the Primordial mound in the forms of frogs and snakes in pairs of males and females (the female names are only feminine variants of the male gods) In the Atlantean version, they seem to have gone out rom there into the four corners of the world while a separate couple, Hathor and Horus the Elder, or Ra, or Ra-Herakhty, stayed behind at the center (The Place of the Center also being an important theme)
There are two versions of this myth depending on whether Ra hatched from an egg or emerged from a waterlily (Lotus)
At any rate, it is easy enough to see where the "Ten Kings" of Atlantis came from: this was later reinforced by a separate tradition of "Ten Kings before the Deluge" represented in Babylon. A version of it is incorporated into the Biblical book of Genesis.
An elaborate bulla with tokens now at the Louvre
The first method of counting was counting on fingers.  This evolved into sign language for the hand-to-eye communication of numbers. But this was not writing.
Tallies by carving notches in wood, bone, and stone were used for at least forty thousand years. Stone age cultures, including ancient American Indian groups, used tallies for gambling with horses, slaves, personal services and trade-goods.
Roman Numerals evolved from this primitive system of cutting notches. The V for five was cut as two notches to represent a person's hand of five fingers (four fingers separated from the thumb by a V shaped gap). The X for ten was cut as two crossed notches to represent two hands.
[It should be noted that some CroMagnon tallies seem to be marked in Roman numerals including I, V and X-DD]
Invention of tokens for record keeping
Globular envelope with a cluster of accountancy tokens, Uruk period, from Susa. Louvre MuseumThe earliest known writing for record keeping evolved from a system of counting using small clay tokens that began in Sumer about 8000 BC. When they wanted to represent "two sheep", they selected two round clay tokens each having a + sign baked into it. Each token represented one sheep. Representing a hundred sheep with a hundred tokens would be impractical, so they invented different clay tokens to represent different numbers of each specific commodity, and strung the tokens like beads on a string. There was a token for one sheep, a different token for ten sheep, a different token for ten goats, etc. Thirty-two sheep would be represented by three ten-sheep tokens followed on the string by two sheep tokens. To ensure that nobody could alter the number and type of tokens, they invented a clay envelope shaped like a hollow ball into which the tokens on a string were placed, sealed, and baked. If anybody disputed the number, they could break open the clay envelope and do a recount. To avoid unnecessary damage to the record, they pressed archaic number signs and witness seals on the outside of the envelope before it was baked, each sign similar in shape to the tokens they represented. Since there was seldom any need to break open the envelope, the signs on the outside became the first written language for writing numbers in clay.
Beginning about 3500 BC the tokens and envelopes were replaced by numerals impressed with a round stylus at different angles in flat clay tablets which were then baked. A sharp stylus was used to carve pictographs representing various tokens. Each sign represented both the commodity being counted and the quantity or volume of that commodity.
About 3100 BC written numbers were dissociated from the things being counted and abstract numerals were invented. The things being counted were indicated by pictographs carved with a sharp stylus next to round-stylus numerals.
The Sumerians had a complex assortment of incompatible number systems and each city had their own local way of writing numerals. In the city of Uruk about 3100 BC, there were more than a dozen different numeric systems. One number system was used for counting discrete objects such as animals, tools, and containers. A different system was for counting cheese and grain products. Another system was used to count volumes of grain and included fractions. Another system counted beer ingredients. Another system counted weights. Another system counted land areas. Another system counted time units and calendar units. And these systems changed over the years. Numbers for counting volumes of grain changed whenever the size of the baskets changed. People who added and subtracted volumes of grain every day used their arithmetic skills to count other things that were unrelated to volume measurements.
The Sumerians invented the wheel and also invented arithmetic. Multiplication and division were done with multiplication tables baked in clay tablets.
Conversion of archaic numbers to cuneiform
Middle Babylonian legal tablet from Alalah in its envelopeBetween 2700 BC and 2000 BC, the round stylus was gradually replaced by a reed stylus that had been used to press wedge shaped cuneiform signs in clay. To represent numbers that previously had been pressed with a round stylus, these cuneiform number signs were pressed in a circular pattern and they retained the additive sign-value notation that originated with tokens on a string. Cuneiform numerals and archaic numerals were ambiguous because they represented various numeric systems that differed depending on what was being counted. About 2100 BC in Sumer, these proto-sexagesimal sign-value systems gradually converged on a common sexagesimal number system that was a place-value system consisting of only two impressed marks, the vertical wedge and the chevron, which could also represent fractions. This sexagesimal number system was fully developed at the beginning of the Old Babylonia period (about 1950 BC) and became standard in Babylonia.
Sexagesimal numerals were a Mixed radix system that retained the alternating base 10 and base 6 in a sequence of cuneiform vertical wedges and chevrons. Sexagesimal numerals became widely used in commerce, but were also used in astronomical and other calculations. This system was exported from Babylonia and used throughout Mesopotamia, and by every Mediterranean nation that used standard Babylonian units of measure and counting, including the Greeks, Romans and Egyptians. In Arabic numerals, we still use sexagesimal to count time (minutes per hour), and angles (degrees).
History of Sumer
History of writing
History of Counting Systems and Numerals. Retrieved 11 December 2005.
1.^ The Earliest Calculating – The Hand, Ifrah (2000), pages 47–61.
2.^ Tally Sticks, Ifrah (2000), pages 64–67.
3.^ The Origin of Roman Numerals, Ifrah (2000), pages 191–194.
4.^ Strings of Tokens and Envelopes, Besserat (1996) pages 39–54.
5.^ Impressed Tablets, Besserat (1996) pages 55–62.
6.^ Tokens, Their Role in Prehistory, Besserat (1996) pages 123–124.
7.^ Archaic Numerical Sign Systems, Nissen (1993) pages 25–29.
8.^ Sexagesimal Place Value System, Nissen (1993) pages 142–143.
 ReferencesDenise Schmandt-Besserat HomePage, How Writing Came About, University of Texas Press, 1996, ISBN 0-292-77704-3.
Georges Ifrah. The Universal History of Numbers: From Prehistory to the Invention of the Computer, Wiley, 2000. ISBN 0-471-37568-3.
Hans J. Nissen, P. Damerow, R. Englund, Archaic Bookkeeping, University of Chicago Press, 1993, ISBN 0-226-58659-6.
It should be noted that Plato's Atlantis story particularly notes that the Kings met on every fifth year and every sixth year alternately, and their numbers frequently show multiples of 6 and 10, hence something like the Babylonian system. The tokens for the standard Babylonian mathematics have already been identified. It also seems that the use of Tokens is also related to the invention of the Abacus and to the use of Quipus (String-records, such as used in ancient Peru)
Also some of the oldest instances of Tokens are recorded in Upper Egypt and the Sudan, going back to possibly 10000 BC or before. And this means that it was possible to transmit the entire Atlantis accounting of their military equipment by means of a set of Tokens fortuitiously preserved through the millenia.
Please note that the accountancy of the Military gear is one thing and the inclusion of the Mythology is another. Plato gave us a recognisable slice of Atlantean Mythology by way of its Egyptian recording, but that does not mean the mythology was actually TRUE. It is useful to know what their Mythology and Religion was like, but that is nothing like an actual historical record. What is recorded in the Critias that is actual practical matter of record is the accounting of the lots and military equipment, and the general description of the land. There was a rumor going around in Ancient times that Plato had gone to Egypt and bought scrolls to add to this dialogue. I would not doubt it because the language used in some of the Critias paassages is unusual for Plato: but this also means it is possible that the exact-accounts parts are added on by Plato as the reults of additional research. That would also clear up the mention of Triremes by Plato when Triremes had not been invented yet in Solon's time. And there is also an implication that the missing end section was also an attached document transcribing an Egyptian myth: Bellamy suggested that and it makes perfect sense.