No one now knows exactly why these queer mounds were made, but learned men have dug into about two thousand of them, and as they have generally found bones, stone arrowheads and axes, beads, mortars, hammers, tools for spinning and weaving, pottery, baskets, and coarse cloth, they think the mounds must have been intended principally as burying places. The beads found in them are very like those which the barbarous Indians called wampum and used as money. Indians wore these beads in strings around their necks, or wove them into belts, using beads of different colors to form very pretty patterns. [Illustration: Wampum.] IV. WHERE THE NORTHMEN WENT. As you have seen in the first chapters of this book, America was once a very different country from what it is to-day. Now you are going to learn how it changed, little by little, from the wild land where Indians roamed about in the huge forests covering the greater part of the country, into a civilized country. We are told that in all the wide territory now occupied by the United States, there were, four hundred and fifty years ago, about two hundred thousand Indians. These were very few inhabitants for so big a country, for now there are many cities here which count many more citizens. The Indians then little suspected that on the other side of the great ocean there was another country, occupied by a race of white men, who knew much more than they did, and who were soon coming to take possession of their land. But the people in Europe, wise as they were, did not know many things which everybody knows now. That was not their fault, however, for they had been trying for several centuries to learn all they could. In the middle of the fifteenth century Europe was already an old country, where long series of kings and queens had ruled over the people. There were then in Europe cities more than two thousand years old, ancient temples and castles, and many of the beautiful Christian churches which people still admire, because none finer have ever been built. The people in Europe had long been great travelers by land and sea, although it was not so easy to get about then as it is now. Indeed, on land they could go only in wagons, in litters, on horseback, or on foot; and on the water they used nothing but rowboats or sailboats, because no one had yet imagined that one could use steam or electricity. On the sea, even the boldest sailors did not dare venture far out of sight of land, for fear they would not be able to find their way back.