SIOUX CITY — A group of six 2020 presidential candidates Tuesday weighed in on issues of importance to Native Americans in a Sioux City forum, and a Native man led off the lineup, giving an extended summary of how white government leaders in the 19th century broke treaties and forcibly moved tribes westward.“He was dropping knowledge on people,” a woman was overheard saying in the lobby of the downtown Orpheum Theatre, at the conclusion of remarks by presidential candidate Mark Charles, a member of the Navajo Nation.In a continuing topic of discussion Tuesday, many candidates said 20 Medals of Honor given to U.S.