Upvote:5
This is the Emirate of Bukhara conquered by Soviet Union n 1920.
So if this map is of 1923, it is somewhat out of date. Though the resistance continued after 1920.
Upvote:8
Expanding on Alex's answer, that beige strip is the Khanate of Khiva and the Emirate of Bukhara, both of which had been reduced to the status of protectorates of the Russian Empire half a century before. They were conquered, disolved an incorporated to the Soviet Union by the Bolsheviks in 1920-1924. Depending of the exact date of your map, how accurate is it and the author's interpretation of the administrative status of the area, the beige strip can be the Emirate and the Khanate or their ephemeral successor entities, the Bukharan People's Soviet Republic and the Khorezm People's Soviet Republic.