like many of our flag images, this is based on research done by the people at crwflags.com (w:Flags of the World).
This particular flag was presented by Ivan Sache on 21 May 1997 [1], citing a paper by J. Renault and H. Calvarin about the flags of Uzbekistan and Turkmenistan in Franciae Vexilla # 5/51 (April 1997):
"The museum of Khiva displays (vertically) the flag used by the khanate of Khiva during the civil war (1917-1922). The khanate, which had been annexed by Russia in 1873, proclaimed independence on 13 February 1917. In 1918, the khan was overthrown by a Turkmen chief. Then began a period of anarchy. The protectorate of Khiva was suppressed on 9 April 1919 and Khiva was included in the new Republic of Khorezm, created by the Soviets on 26 April 1920."