The first theory I came across was one that said that the grass in this part of the Musashi Plain was particularly lush. A quick search for old art depicting any areas of the vast Musashi Plain will yield pictures of tall grasses. Search for plants of the Musashi Plain and all that you’ll see are lush grasses. I don’t see how an area next to the sea would be particularly more luxurious than any other area.
The second theory is that the 斯波氏 Shiba clan had a residence in the area. During the Ashikaga shōgunate, the Shiba were one the families that could hold the position of 管領 kanrei deputy shōgun (literally controller). While the family line came to an end in the mid 1500’s, it’s not impossible to imagine that some member of the Shiba family had a residence here. However, there doesn’t seem to be any collaborating evidence for this theory.
Another theory is that in the early days, when there were many shallow inlets cutting in to what is now central Tōkyō (and this part of town was literally part of the bay, the area was characterized by brushwood used to grow and harvest 海苔 nori seaweed. The general word for brushwood is 柴 shiba*. As far back as the Sengoku Period, we know there to have been a 柴村 Shiba Mura Shiba Village in the area. In the early Edo Period, 柴町 Shiba Machi Shiba Town is attested. The name change reflects an area whose population had grown substantially. In the early Edo Period we start to see an alternate writing as 芝町 Shiba Machi. Over the course of the Edo Period, this new variation becomes the standard and the old variant dies out. Products developed in the area develop a widespread reputation as “Shiba Machi” products – like a brand name.
I couldn’t find anything to explain the change in the kanji or the demand for goods produced in the area, but I have a theory. The shōgunate built a funerary temple complex called Zōjōji in Shiba. As a result, many daimyō residences were also built in the area. I’m willing to bet that the urbanization of the bay front area and controlling the water that flowed in and out of the bay curtailed land/water use in the area. This would have produced more dry land where lush fields of grass might grow instead of mushy wetlands**. The gentrification that came with the arrival of nobles and one of the shōgun family’s main temples would have given the area a lot of prestige. This is all conjecture, but it doesn’t seem unreasonable that lush grass became more of the stereotypical image of the area than swampy inlets filled with half-naked villagers checking their crappy brushwood nets for seaweed. It’s also not unreasonable to assume that as the area had grown in prestige a nice kanji like 芝 (lawn, grass) was preferable to 柴 which looks like something you’d use for kindling in a fire.
Personally, I don’t find any of these satisfying etymologies, but the last one has a lot more to play with. The practice of using 柴 shiba brushwood to harvest nori is apparently still done in a few existing inlets (see picture).
But there is a chronology problem. In 1486, there is a reference to an area called 芝ﾉ浦 Shiba no ura “under Shiba.” This place name uses the “grass/lawn” kanji and not the “brushwood” kanji. The area is noted for salt production and shipping***.
In present day Tōkyō, the south of Shiba is called 芝浦 Shibaura (literally, “under Shiba”). This indicates that the grass/lawn kanji variant may have been in use prior to the Edo Period. It might also suggest that – coincidentally – there were two areas phonetically referred to as しば shiba but – possibly – unrelated to each other etymologically. If this were the case, the alternation of the kanji in the early Edo Period could reflect a confusion or ambiguity about the area that was finally resolved through standardization by the mid-Edo Era – perhaps through a process similar to what I hypothesized above…
…or perhaps not.
So, who the fuck knows? Once again, the origins of another pre-Edo Period place name prove to be elusive. But this time I won’t leave you totally empty handed. As I mentioned before, items produced in Shiba were famous throughout the land in the Edo Period. One of the products was a particularly delicious variety of shrimp that were abundant in the area and brought into port in Shiba/Shibaura. Originally 芝海老 Shiba Ebi Shiba Shrimp was the local name for this species in the area. The species wasn’t specific to this corner of Edo Bay, but the name spread and became the standard appellation for this type of crustacean everywhere in Japan. So while I can’t give you a clear etymology of Shiba, the origins of the name Shiba Shrimp is something we know 100%.
The ironic thing is that these days the water is so polluted that there are very few of them in Tōkyō Bay. Now, most Shiba Shrimp in Japan come from Niigata and Taiwan.
* Compare this to the origin of Hibiya, which is most likely derived from a different method of growing and harvesting nori. (On a somewhat unrelated note, this brushwood kanji is the same character used for 柴犬 shibaken, the famous breed of Japanese dogs.)
** Check out my article on Two Famous Murders to see a picture of nearby Mita/Azabu where you can clearly see “lush grass” growing.
*** Compare this to the origin of Shiodome, which has a salt production theory associated with it.
**** You already forgot what a sandō was?? FFS, have a look at the origin of Omotesandō.