Here is a video of my talk for the American Center for Mongolian Studies. The occasion was the launch of my book, Batu, Khan of the Golden Horde: The Mongol Khans Conquer Russia.
This is a very interesting and informative story. Ms Wolff has put the disparate pieces together in her book. I recommend those interested in the The story of the Golden Horde, read her book. It is an epic story that is little known to western students of history. Make sure to refer to the maps on her website.