Shi'a Islam is practiced by only a small percentage of the population of Tajikistan; a 2009 U.S. State Department report puts the proportion at 3% of the country, compared to 95% for Sunni Islam.
The base of the Shi'a population in Tajikistan is the Pamiri people, who practice Nizari Ismaili Shiism, a variant of Shi'a theology which holds that there is an unbroken chain of living imams down to the present day, currently represented by the Aga Khan, the 49th imam. The Pamiri Ismaili homeland is in Gorno-Badakhshan in Tajikistan's mountainous east, with their spiritual and cultural capital in the city of Khorog.
References
Shia Islam in Tajikistan Wikipedia(Text) CC BY-SA