U+10FBF Chorasmian Letter Samekh

The Wikipedia has the following information about this codepoint:

Khwārezmian (Khwarezmian: زڨاک‌ای خوارزم, zβ'k 'y xw'rzm; also transliterated Khwarazmian, Chorasmian, Khorezmian) is an extinct Eastern Iranian language closely related to Sogdian. The language was spoken in the area of Khwarezm (Chorasmia), centered in the lower Amu Darya south of the Aral Sea (the northern part of the modern Republic of Uzbekistan and the adjacent areas of Kazakhstan and Turkmenistan).

Knowledge of Khwarezmian is limited to its Middle Iranian stage and, as with Sogdian, little is known of its ancient form. Based on the writings of Khwarezmian scholars Al-Biruni and Zamakhshari, the language was in use at least until the 13th century, when it was gradually replaced by Persian for the most part, as well as several dialects of Turkic.

Sources of Khwarezmian include astronomical terms used by al-Biruni, Zamakhshari's Arabic–Persian–Khwarezmian dictionary and several legal texts that use Khwarezmian terms and quotations to explain certain legal concepts, most notably the Qunyat al-Munya of Mukhtār al-Zāhidī al-Ghazmīnī (d. 1259/60).

The noted scholar W.B. Henning was preparing a dictionary of Khwarezmian when he died, leaving it unfinished. A fragment of this dictionary was published posthumously by D.N. MacKenzie in 1971.