Humans in Mongolia are vastly outnumbered by heads of cattle. It's not even a close race. With the numbers in cattle's favor, you're bound to run into some grazing animals almost anywhere you go.
Staying at a Ger hotel? Likely to come across some cattle being herded somewhere. Or in this case, visiting the Erdene Zuu monastery. Taking a walk towards the back of the monastery and all of a sudden, whoa, where did all this cattle come from?