These are created to work as a morph army, based on Early Russians but swapping out some of the early-style elements for later-style ones, and adding a few more Cv elements. The new Cv are all the beautiful Zvezda Russian Knights.
I should also note that Zvezda also produce an even later set of Russian Cavalry for those looking to stretch this army into the C16. I imagine that one could also mix in later Cossack elements and keep morphing right out to the Great Northern War and other conflicts of the early modern Russian state.
Here's a close-up showing the earlier army elements at rear and post-Mongol at front.
Finally here's a wide shot showing the full morph: