Why are people from Holland called Dutch and not Hollish?

Now I need to know...brb.

Ok, here’s what I quickly found:

“Now, what about the Dutch? There are three terms we need to define: Holland, the Netherlands, and Dutch. In Old English dutch simply meant “people or nation.” (This also explains why Germany is called Deutschland in German.) Over time, English-speaking people used the word Dutch to describe people from both the Netherlands and Germany. (At that point in time, in the early 1500s, the Netherlands and parts of Germany, along with Belgium and Luxembourg, were all part of the Holy Roman Empire.) Specifically the phrase “High Dutch” referred to people from the mountainous area of what is now southern Germany. “Low Dutch” referred to people from the flatlands in what is now the Netherlands. Within the Holy Roman Empire, the word “Netherlands” was used to describe people from the low-lying (nether) region (land). The term was so widely used that when they became a formal, separate country in 1815, they became the Kingdom of the Netherlands. The word “Holland” literally meant “wood-land” in Old English and originally referred to people from the northern region of the Netherlands. Over time, it came to apply to the entire country. Got all that?”

http://www.dictionary.com/e/demonym/