In what language does saha mean "island"?

This evening, I have been poring over Danville's beautiful 18th century map of Korea and Manchuria, looking at the tangled area where Korean toponyms give way to Manchu/Jurchen (and other non-Korean) toponyms.

I started out hunting for two places called (in Manchu) ehe kuren and gūnaka kuren, which I expect to find on Danville's map with a spelling like *eghe couren, *counaca couren. I have not found them yet, but I have found something else that is interesting.

All along the Korean coast, small islands are given names ending in tao, which no doubt corresponds to Chinese 島, "island" (Mandarin dǎo).

Some Korean islands with names ending in "tao"

Along the Japanese coast, of course, we have small islands whose names end in sima, corresponding to the Japanese word shima, "island".

Some Japanese islands with names ending in "sima"

But at the mouth of the Tumen river, there is something I did not expect. Some of the islands have names ending in toun, which must be Manchu tun, "island", and some have names in loun, which I am certain is a scribal error for toun. But others have names in saba and saha, which I don't recognize.

A mix of islands with names ending in "toun/loun" and "saba/saha"

I expect saha is a scribal error for saba, because I see the same error in the name of one of the tributaries of the Tumen, called Cahari at one point and Cabari at another. It is more likely that the correct form is saba because intervocalic -h- is rare in these place names, being usually represented by -kh- or -gh-. But in what language does saba mean island?

Note 3 February 2014: It turns out I was wrong. The word is saha, as I note in a later post. I've corrected the remainder of this post.

The major language families of the area (broadly speaking) are Tungusic, Japonic, Korean, Nivkh, Ainu, Mongolic and Chinese. Of all of these, the only thing I have found so far that looks similar is Korean seom 섬, "island", which really looks closer to Japanese shima, as far as I know.

It looks like there is a somewhat large island called mama saha, and a smaller one called sarbatchou saha. Given similar island names throughout the world, it would not surprise me if these are "mother island" and "daughter island", so maybe that is a place to start.

In Manchu, sargan means "woman" or "wife", and sargan jui means daughter. However, Tsintsius lists this as a Manchu morpheme only, not attested in other Tungusic languages, so it falls into what I call the "enigmatic vocabulary" of Manchu: common words with no known origin.

I have often felt that the enigmatic vocabulary of Manchu provides evidence of close contact between the ancestors of the Jurchens and speakers of an otherwise unattested language. Under this theory, words like sargan would have been loaned into Manchu from the other language, which then disappeared. If sarbatchou saha really does mean "daughter island", perhaps it comes from the same source language, or a close relative.

A close study of the place names in Danville's map may lead to more interesting discoveries.