The Icelandic Dotland Saga (c. 1245) tells the story of Bjarni Blood-Axe Sturlnorlasson and his troop of intrepid adventurers who ventured to meet Leif Erikson in Vinland but were blown off course to a place Bjarni Blood-Axe called Dotland. They seem to have landed where the English did a few centuries later, at Savin Hill, which has always been a nice place for newcomers.
Bjarni and his band encountered some of the locals, whom they called skrylings rather than Massachusett and, hungry for fresh meat, they engaged in a little trading. They traded deer haunches for blocks of good Greenlandic cheese they had picked up en route. The Native Americans, being strangers to cows and dairy products, were lactose intolerant. They took their cheeses back to the village and feasted on this new food and woke up the next morning with aching bellies and other, unpleasant digestive symptoms.
After sharpening up their arrowheads and stocking their quivers they made their way to Malibu Beach where Bjarni had beached his long boat (named "Wave-biter" by the way) and drove the vikings from the shores of Dorchester. They were the only Europeans to visit Dorchester until the good ship Mary and John arrived a few centuries later, in 1630 on this very same shore.
What proof do we have that the Dotland Saga contains even a smidgeon of truth? In 1888 a shiny Icelandic dime was recovered from where it was wedged between some puddingstone boulders on Savin Hill. It is another crypto-artifact along the lines of the Dorchester Pot that can only be explained by having been put there by these travellers from a dimly remembered past.