Are Chinese and Iranian "blocky" writing styles related?

Question

Both China and Iran have character styles that are characterized by being (at least approximately) based on a square raster and by "filling up the plane" in the sense that if you take any 2x2 squares from that raster, at least one square will be background and at least one square will not.

In Iran, such writing is often seen on mosques:

(I have marked the word "Allah"/الله)

but it also appears on the national flag:

(this apparently reads "Allahu akbar"/الله أكبر (+ one repetition))

This character style is apparently called "Square kufic" and wikipedia has some more beautiful examples.

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In China, a similar character style is used on seals. These ones appear on a 12th century copy of the famous painting "The night revels of Han Xizai":

And this one on the similarly famous 12th century painting "Along the river during the Qingming festival":

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Now China and Iran are quite distant, which would make it seem as if these writing styles must have emerged independently from each other. However, there actually is an instance where these blocky Chinese seals and blocky Persian/Arabic religious inscriptions were used in the same place at the same time: In Ilkhanid Iran, in the late 13th/ early 14th centuries.

At that time, both Iran and China were ruled by Mongols, and the Mongol rulers in Iran (the Ilkhans) found it politically expedient to recognize the Mongol rulers in China (the Yuan dynasty) as their overlords. For this reason, they received seals from China, and they apparently also made up some Chinese-language seals themselves. Below are seals of the Ilkhans Öljeitü (image source with transcription of the seal, note that the direction of writing seems to vertical and then from right to left) and Ghazan (image source with transcription of the seal, ditto about writing direction):

Öljeitü (the one with the red seal above) had a large mausoleum built for himself which stands to this day, and which houses several square Kufi inscriptions, both inside and, quite prominently, on the outside (image source):

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For what it is worth (but not part of the question), similar styles have been used for the Phagspa script by the Yuan dynasty as well (image source):

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Given the formal similarities between these character styles, I have wondered if these writing styles are related, or if maybe at least one clearly precedes the other. The wikipedia article on Kufic scripts (also linked to above) says the Iranian writing style dates from the 12th century. The Chinese examples I found are on paintings from the 12th century, but I can neither rule out that there are earlier examples, nor that these seals were only added later. Unfortunately the only articles on the Chinese styles that I found were somewhat unspecific.

Answer 1

I can speculate about one possible relationship between the two styles.

Your Persian examples include square seals of Oljeitu and Ghazan.

Ghazan was born 1271 and ruled from 1295-1304.

Oljeitu was born 1282 and ruled from 1304 to 1316.

At that time the Ilkhans were more or less the vassals of the Great Khagan of the Mongols. Since 1271 the Great Khagan of the Mongols was also the Huangdi of the Yuan Dynasty of China.

If those seals were government seals of Ghazan and Oljeitu they might have been made in China and sent by the Great Khagan to the signify appointing Ghazan and Oljeitu to the position of Ilkhan. In which case the writing on them would be in either Chinese seal writing or the Mongolian script.

If the seals were made in Iran they might be in the Persian, Arabic, Mongolian, or Chinese language, possibly written in the square kufic script.

Answer 2

Re. the Chinese writing style, it turns out this particular style is called "Nine-folded seal script" (九叠篆) and first got popular during the Song dynasty in China, first appearing on coins in the 11th century. Note that this particular coin exists in a number of versions, from very readable to very stylized.

This means that if these two writing styles are related, their relation is older than the Ilkhanate or the Yuan dynasty (as stated in the question, the Square Kufic script seems to have been invented in the 12th century). I do not think it is entirely implausible that they are related, but it is also quite possible that they were developed independently from each other.

It might also be worth noting that the creative process is different for the Iranian and the Chinese writing. While the Iranian style is filling up the blank space with lots of simplified writing, the Chinese style is filling the blank space by making the characters more elaborate, e.g. by turning 王 into

,

or 理 into

,