Some sources attribute this flag to a rebellion in Afghanistan from 1929-1930. In " http://www.worldstatesmen.org/INTRO.html ", it is labelled as "(1929 - 1930) Qandahar Rebellion Flag"    
In "http://eh.lenin.ru/english/3as/afghanistan/afg-hist2.htm ", it is labelled as "Flag of Herat Government 1930", which which is the name we use here.  
afghanland.com gives the most detailed description. In " https://web.archive.org/web/20151203191417/http://www.afghanland.com/history/flags/flags.html  ", it is described as "During the rebellion of the son of the water carrier, a flag similar to the Kalakani used in Herat in  the rebellion of the Kohistan."  

It should be noted that all sources have the crescent at a slightly different size.
Own work
Koopinator