For what it's worth, Naqada I-II cultures depicted mountains as triangles on their art, often accompanied by animals of some kind. The number varied.
One might guess that the more stylized / purely geometric patterns were perhaps related
One might venture a guess that ancient Egyptians were thus "obsessed" with that shape long before they built any pyramids, just like the animal figures in their Pantheon could be related to earlier Naqada cultures; see first source for a discussion on that.
Almost every source I've read on the Naqada art says the triangles are mountains. OTOH, there is some informed speculation in one book that some of the earliest dynastic tombs might have used a sand mound (in fact, more than one):
A feature observed at Djet’s tomb was a brick
retaining wall that seems to have enclosed a mound
of loose sand. This mound was entirely subterranean.
It is possible that an additional similar mound would
have formed the superstructure of the tomb, and
probable that other tombs at Umm el-Qaab would
have had similar features now destroyed (Dreyer
Furthermore, there's speculation that some of the predynastic tombs might have used an earth mound as cover:
1894 [Koptos Petrie] started work at the site of Naqada, where
he was finally to find the evidence he so desired of
Egyptian culture before the pyramid age. Naqada
turned out to contain an immense cemetery, in which
Petrie and his team cleared over 2,000 graves in just
over three months [...]. The dead had been
placed in graves covered over originally with brushwood and low mounds of earth that had collapsed
onto the burials, many of which had been robbed in
So yeah, it's also possible they might have been depicting their own contemporary grave designs as well.
Interestingly enough, the Naqada II graves of the elites were surrounded with large pits full of animal bones, neatly segregated by category: dogs, goats, bulls, boobons, and even an elephant is found at the HK6 cemetery site in Hierakonpolis/Nekhen. (In fact the list/variety of animals buried there is a bit longer than given in that book.)
Since another answer pointed out that the egg is from the nearby A-Group culture actually (I took claim in the Q at face value above), it turns out that this culture too liked triangles, for whatever reason, although we have a lot less nice pictures of that:
Painted Eggshell ware SJE 277:49, 332:53B
(SJE stands for "Scandinavian Joint Expedition to Sudanese Nubia".)
That paper also discusses that the A-Group had a combination of Naqada and Sudanese pottery imports. OTOH, the A-Group graves were generally simple pits.
Another one from the Franco-Argentine Archaeological Expedition in Sudan (also found in A-Group dig) alas only shown as a schematic:
At least the regular triangle patterns were encountered on the seemingly older Neolithic pottery found in Sudan, like this one from the Kadero dig.
By the way, whether something neolithic with triangles is or isn't a map has been hotly debated on some occasions, such as regarding the Tepe Gawra "Landscape Jar" (discovered in Iraq, should be exposed/located at the Iraq Museum, Baghdad, but there don't seem to be any recent pictures of it)
One of twelve decorated panels, this is by
far the most complex and unusual. The juxtaposition of animal figures (absent from other panels), parallel lines of triangles (commonly found on pottery representing mountains), and the sinuous herringbone pattern down the middle (interpreted as a river with its tributaries) led one excavator to suggest the panel portrayed a landscape or even a map of a specific area.
From Arthur J. Tobler, Excavations at Tepe Gawra: Joint
Expedition of the Baghdad School and the University Museum
to Mesopotamia, 2 vols. (Philadelphia: University of Pennsylvania Press, 1950), vol. 2, pI. LXXVIIIb.
The interpretation of the Landscape Jar has already
proved controversial. Ten of the twelve painted panels
that make up its decoration contain linear and geometric
patterns. One of the other two contains what A. J. Tobler
concluded was not just a landscape painting but "a kind
of map.... probably the oldest map yet discovered."
According to Tobler, the painting shows a hunting scene
in a broad valley, the latter flanked by mountains (in-
dicated by the two rows of triangles) and containing the
tortuous course of a river with its tributaries (figs. 4.15
and 4.16). He also suggested that the artist must have
had some real landscape in mind. However, not all agree
either with this interpretation or with his interpretation
of the ten geometric panels as representations of different
types of terrain such as rolling plains, mountains, deserts, and marshes. Beatrice Goff, for instance, considers the scene to be a highly schematized and not uncommon form of decoration that was a means of giving
expression to "deep-seated feelings of aggression" rather
than a representation or a picture of a familiar landscape.
Anyhow, if the Nubian egg is a map, and the hashing or zigzag on it is a river, then there are certainly some features in the Western Desert that would be suitable mountains, at least as a rough reference point.
Oh, and to make the debate a tad more interesting, it turns out one of the two initial images in this post has also been suggested as a cosmological map.
The bowl dates from the Amratian period, mid-fourth millennium B.C.
Giedion sees this as portraying in abstract form the
course of the sun from east to west, the enclosing primeval ocean, and the two central mountains of East and
West, and indeed there is widespread acceptance of such
an idea in the interpretation of decorated pottery from
the Middle East and sites such as Susa.
And it turns out that a Susa [this way over in Iran] pot (dated 4200BC-3800BC according to the British museum) has... three triangles among other things among its design patterns. But I don't know of mythical interpretation for three (rather than two) triangles. OTOH the number probably doesn't mean anything specific in that case, because there are very similar Susa pots with four triangles.