Thats correct if we talking about modern population of Volga region. Volga Bulgaria was annihilated in 1236 from Tataro-Mongol hordes. The next state units in the region didn`t accept Volga Bulgaria as their ancestor, but the Golden Horde. The locals of Russian republic Tatarstan could have some DNA of the old Bulgars, but Turkic and Mongol legacy is totally dominant. Only in the last years began discussions in some nationalistic circles in Tatarstan for connection with Volga Bulgaria. Тo justify their indigenous and to get prestige of the civilization, built great cities like Bolğar, Qaşan, Suvar and many others. If you go to any Russian-speaking history forum, you will see bitter debate between two party- "Bolgars" and the proud successors to the conqueror Genghis Khan. Of course the "Bolgar" party imagine Volga Bulgarians as Turkic speaking Turkic tribe.