A team of Dakota riders are in Mankato after a 330-mile trek through frigid, snowy weather.  The end of the ride marked the 160th anniversary yesterday of the largest mass execution in American history.  It honors 38 Dakota killed on that day in 1862, plus two who were captured and killed later.  Hundreds turned out to welcome the riders, who began their trip in Lower Brule, SD and retraced the route of Dakotas who were forced out of Minnesota and onto a South Dakota reservation.  Organizers say this is the last remembrance ride, and that a new tradition will be honored starting next year.