[92] Trans. Hist. and Lit. Com. Am. Phil. Soc. Vol. 1, Philadelphia, 1819. [93] Seneca tradition, N. Y. Hist. Col. vol. 2. At what era the Alleghan confederacy, thus shadowed forth, existed and fell in North America, we do not know. Our Indian nations have no certain chronology, and we must establish data by contemporaneous tradition of the Mexican nations, or by internal antiquarian evidence. The “Old Fort” discovered by Dr. Locke in Highland Co. Ohio in 1838, denoted a period of 600 years from its abandonment,[94] that is, 284 years before Christopher Columbus first sailed boldly into the Western ocean. The trees on Grave Creek mound denote the abandonment of the trenches and stone look-outs in that vicinity to have been in 1338. (Trans. Am. Ethnological Society, vol. 1, N. Y. 1845.) The ramparts at Marietta had a tree decayed in the heart, but the concentric outer circles, which could be counted, were 463. (Clinton’s Dis.) The live oaks on the low mounds of Florida, where one of the Algonquin tribes, namely, the Shawnees, aver that they once lived and had been preceded by a people more advanced in arts (Vide Arch. Am. vol. 1.) denote their abandonment about 1145. But even these data do not, probably reach back sufficiently far, to denote the true period. [94] Cincinnati Gazette. If we fix upon the twelfth century as the era of the fall of the Alleghan race, we shall not probably over estimate the event. They had probably reached the Mississippi valley, a century or two before, having felt, in their original position, west and south of that stream, the great revolutionary movements which preceded the overthrow of the Toltec and the establishment of the Aztec empire in Mexican America. There are but two words left in our geography, supposed to be of the ancient Alleghan language. These are Alleghany, and Yioghiogany, the latter, being the name of a stream which falls into the Monongahela, on its right bank, about twenty miles above Pittsburgh.