I live in Arkansas - 105 in the summer and below 20 in the winter, lots of snow at times.
My shrubs were here when we moved in so I've identified them as a Japanese Holly - they're evergreen with small leaves and small decorative black berries (I might be wrong with my identification on this, though), which is great for a privacy-shrub - and seem to handle our weather very well.
Two years ago we cut quite a few of them back to remove our old storage shed and they came back rather quickly - and now they are an immense 10' high. But they can be pruned with a fair amount of ease. They're not like a Box which is very dense, they are loose and if left untamed the branches will get long and droop.
We liked these so much, and they handle our soil so well, that we've picked the seedlings that grew and planted them around the yard - we went from having a small area of a few trees to an entire privacy fence that's lined with them.
They're excellent and make it through the toughest heat, worst storms and heaviest ice.
IF these are not a Japanese Holly then I have no clue what they are