TheLiberator236 isn’t trolling: They move ridiculously fast!
Especially compared to infantry units, which have difficulty even chasing him, which they shouldn’t have to.
With the Ovoo upgrade of “Superior Mobility (Improved)”, his speed increases from 0.75 to 1.35, and under the influence of the Ovoo with the Ortoo Net effect, it can increase to “1.55,” faster than any infantry.
If you really expect them to move even faster, it will be impossible for any civ to chase down the Mongol landmarks if the enemy goes to great lengths to conceal them.