Normans founded kingdoms between which there was a lively interchange
of visits and knowledge.

They certainly extended their voyages to Greenland, and there is a
good deal of evidence for believing that they travelled from Greenland
to Labrador and Newfoundland. In the year 1001, an Icelander named
Biorn, sailing to Greenland to visit his father, was driven to
the south-west, and came to a country which they called Vinland,
inhabited by dwarfs, and having a shortest day of eight hours,
which would correspond roughly to 50° north latitude. The Norsemen
settled there, and as late as 1121 the Bishop of Greenland visited
them, in order to convert them to Christianity. There is little
reason to doubt that this Vinland was on the mainland of North
America, and the Norsemen were therefore the first Europeans to
discover America. As late as 1380, two Venetians, named Zeno, visited
Iceland, and reported that there was a tradition there of a land
named Estotiland, a thousand miles west of the Faroe Islands, and
south of Greenland. The people were reported to be civilised and
good seamen, though unacquainted with the use of the compass, while
south of them were savage cannibals, and still more to the south-west
another civilised people, who built large cities and temples, but
offered up human victims in them. There seems to be here a dim
knowledge of the Mexicans.

The great difficulty in maritime discovery, both for the ancients
and the men of the Middle Ages, was the necessity of keeping close
to the shore. It is true they might guide themselves by the sun
during the day, and by the pole-star at night, but if once the
sky was overcast, they would become entirely at a loss for their
bearings. Hence the discovery of the polar tendency of the magnetic