I Migratory period ?-200 II Golden Age or Old Empire 200-600 III Colonization period 450-700 IV Transitional period 700-1000 V Renaissance or League period 1000-1200 VI The period of the Toltec mercenaries 1200-1450 VII Disintegration 1450-1541 VIII Period of wars with Spain 1519-1697 Before taking up our review of the first seven periods we must remind ourselves that the prehistoric cultures of Middle America have a certain unity, showing beyond doubt that they were all of a common origin. It is impossible to tell at what epoch the Maya became separate and distinct from the other highly cultured peoples scattered over Mexico and Central America. Fortunately, however, owing to the investigations in the Valley of Mexico, we have abundant material for the reconstruction of the sequence of cultures. Three successive strata of occupation have been found in the Valley of Mexico. The earliest of these, the Archaic, is also found in many other places throughout Mexico and Central America. There is some reason to suppose that this culture was at one time fairly uniform throughout the greater part of Middle America. The local developments seen in the Maya, the Zapotec, and the early Mexican cultures may have been the result of modifications of the Archaic culture. Above this Archaic stratum in the Valley of Mexico is found the Toltec or Teotihuacan culture. This is synchronous with late Maya of the sixth period on our table. Manifestations of its art are found in the latest buildings at Chichen Itza. I. Migratory Period (?-200 A.D.). The two earliest dated Maya inscriptions that we have are those on the Tuxtla statuette and on the Leyden plate. (Morley, 1915, p. 194 ff.; Holmes, 1916.) The former is dated, in the Maya system of chronology, 8.6.2.4.17. (about 100 B.C.); the date on the latter is 8.14.3.1.12. (about 50 A.D.).[1] Although, as Mr. Morley points out, these are the earliest dates we know of from the Maya area, it is to be noted that they do not differ essentially from the more recent inscriptions. They ought, therefore, to be regarded as introductory to the historic period, and it may be assumed that they were themselves preceded by many decades of development during which the first attempts at writing were gradually elaborated until the extremely complex Maya hieroglyphics were evolved in the form in which we know them.