The Great Pueblo Period of 1100 to 1300 A. D. was the climax of Pueblo development in the Mesa Verde. From 1100 to about 1200, the people lived on the mesa tops in well-built masonry pueblos. The plan of the villages, however, began to change. Kivas, which formerly had been outside the village proper, were now placed inside and were surrounded by houses. Tall, round towers, which may have been lookout towers, became common. The villages also grew larger and were concentrated in the most favorable areas. All of this indicates a need for defense and it is probable that nomadic Indians were beginning to harass the Pueblo farmers. About 1200 A. D., the Mesa Verde people began to move to the caves. Soon most, if not all, were living in cliff dwellings which were simply pueblos built in caves. This abrupt change evidently resulted from a need for defense against increasing enemy pressure. During this last century, the people reached their highest level of development. Houses, pottery and all other arts and crafts except basketry were of the finest quality produced in the Mesa Verde. After thirteen centuries of steady development, the culture reached its peak. In 1276 A. D., a drought began which lasted through 1299 A. D. Because of the drought and probably, also, because of increasing enemy trouble, the people moved to the south. Some of our modern Pueblo Indians living in New Mexico and Arizona are their descendants. The Mesa Verde was never again occupied by farming Indians. After many silent, empty centuries, the cliff dwellings were discovered by the white man in 1874. Transcriber’s Notes —Silently corrected a few typos. —Retained publication information from the printed edition: this eBook is public-domain in the country of publication. —In the text versions only, text in italics is delimited by _underscores_.