The creator's definition of a "battle" is very different than how most people would define them. A just one example: this site considers the 1980 siege at the Iranian Embassy in London as a battle, which I doubt most people would agree with.
http://dbpedia.org/page/2007_United_States_Air_Force_nuclear...
There also seems to be a surprising lack of battles across the eastern steppes by the Mongols.
Definitely could use some more information of how they decided what a battle is - or the data source at least
But the data for much of their conquests doesn't exist.
Did you know Texas and Oklahoma fought a "battle"? http://dbpedia.org/page/Red_River_Bridge_War
A battle between bridge trolls.