Wikipedia says 30% of 3.5 million are "nomadic or semi-nomadic", which would be 6 people to a yurt. I couldn't figure out what percentage of the country was done, but if he did 270,559/37,258,617 zoom 17 tiles then there could be another 100k in the other 99% of the data.
Living away from other people and not next to anything in particular is what I associate with nomads, the heuristic of searching a radius around landmarks doesn't make sense to me. I scrolled around a random remote desert area in Mongolia on Google Maps and found a yurt every couple of minutes.
172k of them? That still seems like quite a lot of yurts; certainly more yurts per capita than anyone else has.