The IEP entry on Anaximander has:
The astronomy of neighboring peoples, such as the Babylonians and the Egyptians, consists mainly of observations...In contrast, there exists only one report of an observation made by Anaximander...for Anaximander’s merits do not lie in the field of observational astronomy, unlike the Babylonians and the Egyptians, but in that of speculative astronomy.
We may discern three of his astronomical speculations:
(1) that the celestial bodies make full circles and pass also beneath the earth,
(2) that the earth floats free and unsupported in space, and
(3) that the celestial bodies lie behind one another.
Notwithstanding their rather primitive outlook, these three propositions, which make up the core of Anaximander’s astronomy, meant a tremendous jump forward and constitute the origin of our Western concept of the universe.
The idea that the celestial bodies, in their daily course, make full circles and thus pass also beneath the earth – from Anaximander’s viewpoint – is so self-evident to us that it is hard to understand how daring its introduction was. That the celestial bodies make full circles is not something he could have observed, but a conclusion he must have drawn
What catches my attention is the discussion of the Egyptian Solar God Ra who was established as a major deity by the time of the fifth dynasty circa 2400 BC. He is said to travel on two solar boats:
called the Mandjet (the Boat of Millions of Years), or morning boat and the Mesektet, or evening boat. These boats took him on his journey through the sky and the Duat, the literal underworld of Egypt
In this mythological picture, Ra sails through the sky from the West to the East on the morning boat and then through the underworld, that is under-the-world on the evening boat from the East to reappear in the West. Although it is not described as a circle it is at least a continuous circuit so is topologically a circle. Ra himself is preserved through the circuit. He goes above & under the world.
The parallel with the first statement that the IEP makes and finds so daring I find quite startling. Given the possibility of one parallel, are there not likely to be more?
Are there standard works that explore connections between Babylonian & Egyptian cultures and the Presocratic tradition?
Notably there aren't myths of either Helios or Apollo that can have the same parallel that Ra does here. (Helios crosses the sky in a Chariot but sails back on the oceanus back to the East).