Lyndon B. Johnson is the answer
It changed how the big businesses/monopolies worked. In which workers could work shorter hours for a tad bit more pay. Women were given the chance to vote. And tenements were required to be in better condition for immigrants.
But the Mongol Empire left other legacies: the Silk Road and its history of trade; cultural development; and the potential for a modern era characterized by the unity of disparate peoples, and relative peace.
