As they spread, they encountered people of other stocks, with whom they had frequent wars. Their most constant and most dreaded enemies were the tribes of the Algonkin family, a fierce and restless people, of northern origin, who everywhere surrounded them. At one period, however, if the concurrent traditions of both Iroquois and Algonkins can be believed, these contending races for a time stayed their strife, and united their forces in an alliance against a common and formidable foe. This foe was the nation, or perhaps the confederacy, of the Alligewi or Talligewi, the semi-civilized "Mound-builders" of the Ohio Valley, who have left their name to the Allegheny river and mountains, and whose vast earthworks are still, after half-a-century of study, the perplexity of archaeologists. A desperate warfare ensued, which lasted about a hundred years, and ended in the complete overthrow and destruction, or expulsion, of the Alligewi. The survivors of the conquered people fled southward, and are supposed to have mingled with the tribes which occupied the region extending from the Gulf of Mexico northward to the Tennessee river and the southern spurs of the Alleghenies. Among these tribes, the Choctaws retained, to recent times, the custom of raising huge mounds of earth for religious purposes and for the sites of their habitations, a custom which they perhaps learned from the Alligewi; and the Cherokees are supposed by some to have preserved in their name (Tsalaki) and in their language indications of an origin derived in part from the same people. Their language, which shows, in its grammar and many of its words, clear evidence of affinity with the Iroquois, has drawn the greater portion of its vocabulary from some foreign source. This source is conjectured to have been the speech of the Alligewi. As the Cherokee tongue is evidently a mixed language, it is reasonable to suppose that the Cherokees are a mixed people, and probably, like the English, an amalgamation of conquering and conquered races. [Footnote: This question has been discussed by the writer in a paper on "Indian Migrations as evidenced by Language," read before the American Association for the Advancement of Science, at their Montreal Meeting, in August, 1882, and published in the American Antiquarian for January and April, 1883.]