7. In some tribes we find a head chief, whose power, however, is limited. He is one of the sachems who has to take provisional measures in cases requiring immediate action, until the council can assemble and decide. He represents a feeble, but generally undeveloped prototype of an official with executive power. The latter, as we shall see, developed in most cases out of the highest war chief. The great majority of American Indians did not go beyond the league of tribes. With a few tribes of small membership, separated by wide boundary tracts, weakened by unceasing warfare, they occupied an immense territory. Leagues were now and then formed by kindred tribes as the result of momentary necessity and dissolved again under more favorable conditions. But in certain districts, tribes of the same kin had again found their way out of disbandment into permanent federations, making the first step towards the formation of nations. In the United States we find the highest form of such a league among the Iroquois. Emigrating from their settlements west of the Mississippi, where they probably formed a branch of the great Dakota family, they settled at last after long wanderings in the present State of New York. They had five tribes: Senecas, Cayugas, Onondagas, Oneidas and Mohawks. They lived on fish, venison, and the products of rough gardening, inhabiting villages protected by stockades. Their number never exceeded 20,000, and certain gentes were common to all five tribes. They spoke closely related dialects of the same language and occupied territories contiguous to one another. As this land was won by conquest, it was natural for these tribes to stand together against the expelled former inhabitants. This led, not later than the beginning of the fifteenth century, to a regular "eternal league," a sworn alliance that immediately assumed an aggressive character, relying on its newly won strength. About 1675, at the summit of its power, it had conquered large districts round about and partly expelled the inhabitants, partly made them tributary. The Iroquois League represented the most advanced social organization attained by Indians that had not passed the lower stage of barbarism. This excludes only the Mexicans, New Mexicans and Peruvians. The fundamental provisions of the league were: