Hello!
Here are the ruling authorities I could find for Volga Bulgaria (volga_bulgaria). All have examples listed on Numista.
https://www.zeno.ru/showgallery.php?cat=921
Volga Bulgaria
Almysh, Emir, circa 920s, Q657805 (N#150169)
Yaltavar, Emir, circa 920s (N#150180)
Mikaʾil ibn Jaʿfar, Emir, circa 910s-920s (N#150153)
Abdallah ibn Tegin, Emir, circa 920s-1230s (N#150181)
Talib ibn Ahmad, Emir, circa 950s (N#150165)
Abdallah ibn Mikaʾil, Emir, circa late-950s (N#150166)
Muʾmin ibn al-Hasan, Emir, circa 970-987 (N#150173)
Muʾmin ibn Ahmad, Emir, circa 977 (N#150176)
Abd ar-Rahman ibn Muʾmin, Emir, circa 997 (N#150178)
Most are only known by their coins, with exact dates of rule not being certain. Aside from Yaltavar and Abdallah ibn Tegin), the rulers are all mentioned here: https://en.wikipedia.org/wiki/List_of_rulers_of_Volga_Bulgaria
