Apparently, the Vikings discovered how to freeze-dry sea fish - which made it easy for them to transport them to settlements around Europe
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Noted especially because of how we underestimate both the ingenuity and trade links of those humans who went before us.
The last line is very true, but I have an elaboration and a correction that may interest you.
Elaboration
The concept of air-drying certain fish (i.e. non-oily ones), had been known for millennia. Likely, too, the use of lye (derived from potash). The word for the resulting air dried and lye-treated food is lutefisk (lyefish) -- in Finnish lipeäkala and, more humorously, saippuakala (literally, 'soap fish'). I have researched the Neolithic, and this method of preservation seems wholly defensible then. I have also studied the Vikings to a certain degree, and found that, b/c of their stocking up for brutal winters, they were well aware of the provisions needed for maritime excursions. (They had a knowledge that southerners did not, for a change. Otherwise, the northerners were rather backwards. E.g. the Iron Age came much later for them.)
Correction
I suspect the article is what you will see when a journalist, undereducated in science, writes about science. As someone well educated in science, I notice this sort of reporting often.
Freeze drying involves the sublimation of water under a vacuum. This technology was not available to the Vikings. Water does not readily sublime at atmospheric pressure, though I grant it could have occurred, in part and very slowly -- much like what we now see in our freezers, when we leave food in a sealed bag for a long time. Note that some, but not most, of the water in frozen food can accumulate as snowy-ice. This process is a largely incomplete version of, say, making freeze-dried coffee -- where the water is wholly removed.
In sum, the Vikings built on their ancestors knowledge with their own advancements, yes, but not in food preparation (at least as far as I have found).
