In Kazan were the roots of many famous Tatar merchant families. The rules and traditions of commercial affairs were born here; here since the time of the Khan there was an ancient knot that connected the trade interests of many foreign states. Tatar merchants and everyone else should be credited with the fact that "the city... Kazan - as Mikhail Rybushkin, a professor at the Imperial Kazan University, wrote in his work "A Brief History of the City of Kazan" in the 1st half of the 19th century - both in the former and at present was and is the subject of the most important internal trade..."