I know the Mongols weren't the only ones and that steppe hordes had harrassed settled communities in Europe, the Middle East and China for thousands of year. But somewhere around 1800-1600, it seems these kingdoms/empires faded out of history. What was the reason for this? Was it the sheer manpower and organization advantage of nations at the time, or was it a specific tactical advancement that caused their decline?

Also, how did these hordes evolve with time? How different were the Huns, Parthians, Mongols, Manchus etc. from each other? Thank you :)