Ancestry from Kazakhstan

My mother-in-law bought me a DNA test from Ancestry.com as a Christmas present. It's something I would have never done for myself, but I thought it might be interesting. My ancestry has been documented for several hundred years on most lineages, so I certainly didn't expect any surprises. 

Despite my expectations, my "ethnicity estimate" held one major surprise. Between nine and thirteen percent (9-13%) of my DNA comes from Central Asia! This portion of my ancestry supposedly comes from somewhere near Afghanistan, Kazakhstan, or Turkmenistan. 

To understand the significance of this estimate, my grandmother's grandmother was full Irish. That was only four generations ago, but Ireland provided only six percent (6%) of my total ancestry. The exact percentages are questionable in my mind, but if the pattern is consistent, that would mean that someone closer than four generations was from Central Asia, or that more than one ancestor came from that lineage. 

I'm not sure what any of this means. I'm not even sure the estimate is reliable, but it sure makes me wonder.