The mysterious, mathematical origins of the world's most unusually shaped national flag

A man carries a Nepalese flag as he stands outside his stall in Kathmandu, Nepal, Wednesday, Sept. 16, 2015. ( (AP Photo/Niranjan Shrestha)

It’s a go-to question at bar trivia: what is the only national flag in the world that isn’t rectangular or square shaped?

The answer is Nepal. But beyond the simple fact of its uncommon shape, Nepal’s flag is a bit of a mystery.

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Depending who you ask, the flag represents the movement of the heavens, modern nation-building, Buddhist and Hindu legacy, Asian pride, political maneuvering or some combination of all of them.

The flag is easily spotted among its peers: it is comprised of two crimson-colored rightward-pointing isosceles triangles, decorated with a navy blue border and two white shapes that represent the sun (on the lower half) and the moon (on the upper one).

“That particular shape, the single pennon and double pennon, is not unique to Nepal. It has a long and deep history in South Asia and in the Indian subcontinent,” explains Sanjog Rupakheti, a professor of history at the College of the Holy Cross in Massachusetts and a Nepal native.

“We were taught in school growing up that the sun and moon … represent the eternity of the nation, triangles supposedly representing the (Himalayan) mountains that Nepal is known for. As a historian, I think a better and a more persuasive interpretation would be to see these symbols as representing these mythical, ancient, illustrious dynasties that many ruling elites in the region often styled their genealogy after.”

Some people believe that the red color represents Nepal’s national flower, the rhododendron, while others say it’s meant to symbolize war and bravery.

Rupakheti is quick to point out that even Nepali history scholars aren’t completely sure about the full backstory of the national flag.

Weaving a history

One of the earliest depictions of the flag comes from sketches by Henry Ambrose Oldfield, a British doctor and artist who lived in Nepal in the mid-1800s. English journalist and travel writer Perceval Landon also talked about a double pennon flag in his book “Nepal,” which was published in 1928.

Although Landon’s picture of the flag was in black and white, he includes a footnote clarifying the flag’s border was green, not blue.

Previous versions of the flag, including the ones drawn by Landon, depict the sun and moon with human faces.

Before the establishment of democracy in Nepal – originally in 1990, then again in 2008 – it was forbidden for most regular Nepalis to display flags at their homes.

“National flags could only be unfurled and could only be displayed at government premises,” explains Rupakheti. “There were definitely very strict guidelines, not just on the shape and size, but also when, how, and who could display a flag. But that gradually began to change with the opening up of the democratic experiment. And now it’s everywhere.”

Nepal’s flag is a popular one among flag obsessives, who refer to themselves as vexillologists. Ted Kaye, secretary of the North American Vexillogical Association (NAVA), says that the flag’s history and shape make it a common conversation topic.

“Maps and flags have an interesting cultural and geographical overlay,” says Kaye. “The rest of Asia has given in to the colonial view that a flag should be a rectangle, but Nepal is this holdout that connects to the history flags of Asia.”

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Trivia junkies may be drawn to Nepal’s flag for its non-quadrilateral shape. But the flag is also studied by mathematicians.

“It’s the nerdiest mathematical flag that is out there,” Kaye adds.

In 1962, King Mahendra asked a mathematician to develop precise specifications for the size and shape of the Nepali flag that would be used to standardize the flag. Those specifications are enshrined in Nepal’s constitution.

Among the rules: the sun must have 12 rays, both the sun and moon must be white, and the border color is specified as “deep blue.”

As for the rest, it’s probably better to have advanced knowledge of geometry to make sure you’re doing it right.

Nepal’s unusual flag shape has also become a challenge for international events. At the Olympics, there is a rule that all flags must be displayed in a 2x3 ratio, which can result in some of them looking oddly stretched out.

Though some previous Olympics organizers have attempted to standardize the Nepali flag by sticking it on a white rectangular background, the IOC ruled that Nepal’s flag can remain as is.

Nepal is, once again, a proud exception to the rule.