But isn't yoghurt more-or-less authentic for mongol cooking? Assuming you don't have a herd of horses handy.

If I cook Thai I use coconut milk, not cream. When I cook traditionally olive oil based stuff, I use that, not butter. But cuisines were developed on certain ingredients. You simply can't make French or northern Italian without butter and cream. Similarly it would be a bit difficult to make Chinese butter and cream based - you could try, and perhaps fiddling around you might make something edible, but why?