It was a 3D animated TV show that ran on Slovak (or maybe Czech) television sometime between 2004 and 2013. I am sure it is a foreign show, since neither of these countries had produced animated TV shows at that time (that I know of).
The show was about three tribes of prehistoric people. The land they lived in was shown at the start of each episode (?) and was split three ways with mountains of some sort. There was a tribe of farmers, a tribe of hunters and a tribe of barbarians and each of them lived separately.
If I remember correctly there was a girl from the farmer tribe and a boy from the hunter tribe that were the main characters.
One of the tribes (maybe the farmers) knew how to count, but knew only the numbers one and two. When they had to count more things they repeated the numbers eg. if they had to count 5 sheep, they would count it as 2, 2 and 1. In one of the episodes an old hermit-y person from one of the tribes discovered additional numbers (3 and 4) and later (maybe in the same episode) the number 0 and 10 (or 100?) - in the process of discovering these new numbers, he marked trees in a forest with scratches. I seem to remember an X on a tree.
I don't remember much of the plot, but people of the tribes obviously met somehow and started interacting with each other, with the barbarians being the "bad guys" - they ware big, muscular and somehow round (?) compared to the other more stick-like characters. I also seem to remember they rode some brownish animal (possibly a boar, but I am unsure). I believe the girl was the more important of the two main characters and her father was somehow mysterious or something (I am very unsure about this part).