The orange color are a little strange !
I wondered about that, but a quick Google search showed that some historians believe the Mongolians introduced orange dye to China, the source of the dye being Saffron flowers, so it is quite possible that Mongolians used Saffron to dye their clothing orange.
Orange boots? One might expect black or brown, but Playmo love their highly colored footwear. Yet here again, maybe Playmobil did their research:
Mongolian Boots
It could be that they just happened to choose orange becaused they had large stock of orange plastic pellets, but whether by design or happy accident, it seems orange is a viable color for both Mongolian fabric and leather!