Human sacrifice among the Maya was probably a somewhat rare event, taking place only on extraordinary special occasions, as in times of public calamity--for example, during the prevalence of famine, war, or pestilence--when it was felt that a special propitiatory offering to the god was called for. This practice was confined to one, or at most to a very small number of victims, never reaching the proportions which it did among the Aztec, by whom it was probably introduced into Yucatan. The main offering of the Maya to their gods seems to have consisted of an incense composed of copal gum and aromatic substances. Landa mentions this as largely employed at the time of the conquest; Villagutierre encountered it among the Itza at the end of the seventeenth century; and Tozzer found it in use among the Lacandon Indians at the present day. The incense itself has been found all over this area, as well as great numbers of incense burners. In addition to incense, the blood of fish, birds, and animals was smeared over the images of the gods, as an offering, together with human blood obtained by cutting the ears, tongue, genitals, and other parts of the body. The hearts of various animals, together with live and dead animals (some cooked and some raw) and all kinds of foods and drinks in use among the people,[23] were also employed as offerings to the gods. In the hands of figurines upon the incense burners are found, modeled in clay, fruit, flowers, eggs, cakes, birds, small animals, and other objects, all evidently intended for the same purpose. CHRONOLOGY Three distinct periods of Mayan civilization seem to be represented in this area. The center of the earliest of these was along the Rio Grande, in southern British Honduras, within 20 miles of the Guatemala frontier, where the Leyden Plate was discovered, upon which is inscribed the earliest but one known Maya date--namely, Cycle 8, Katun 14, Tun 3, Uinal 1, Kin 12. If the massive stone-faced pyramids and terraces of these ruins are contemporaneous with the Leyden Plate, as seems possible, they must be reckoned among the earliest monuments of the first, or southern Maya, civilization. The Benque Viejo temple, in the extreme western part of British Honduras, comes next in point of time. This was almost certainly contemporaneous with its near neighbor, Naranjo, where the earliest Initial Series found is 9.10.10.0.0, and the latest 9.19.10.0.0, giving the city an age of at least 9 katuns, or 180 years. It will be seen that the difference between the Leyden tablet date and the earliest recorded date at Naranjo is rather more than 16 katuns, or 320 years.