What is "purgaz"

Purgaz or Inäzor Purgaz (, , Purgas) was an Erzän leader in the first half of the 13th century. He was a Grand Duke (inäzor) of the Erzän Principality of Purgaz. Being an ally of Volga Bulgaria, he resisted Suzdal Russia's expansion into the region. In later times, he became a symbol of Erzän independence and a figure of legend.