challenge: Where was the Northwest Siberian trans-Ural trade colony of Mangazeya founded by Cossacks from Tobolsk in 1600?
  
  A. On the Volga River
  B. On the Irtysh River
  C. On the Taz River, between the lower courses of the Ob and Yenisei Rivers
  D. On the Amur River
  Answer: 