Brachycephaly and external pressure

Browsing through some literatures, I happened to find out some records on the rite of imitation of the child's head to brachycephaly. In 1976, two skulls showing extraordinary forms were excavated out of an ancient tomb at Yean village of Daedong township in Kimhae County in Kyungnam Province, the Republic of Korea. The deformation in Yean village is judged to be an intentional frontal flattening. The frontal bone of deformed individuals is remarkably flattened by a primary deforming force. The parietal bone expands laterally and superoposteriorly as a major compensatory growth. The lambdoid or occipital flattening induced by the counterforce is light and unstable. In the facial skeleton, the maxilla shifts downward as a minor compensatory growth. These findings might be substantially correspondent to the custom in the southern area of Korea in the 4th century A.D. paragraphed by Han chuan of Wei-dynasty record, History of the Three Kingdoms. It described that the people gave a pressure onto the child's forehead with stones in order to mold it for preference. Flatheaded meant "free" among the Chinook and Salish tribes of American Indians. Babies of slaves were denied the year-long beauty treatment--a board tied to the infants' padded skull--that permanently flattened the foreheads of tribal members. Referring to these records, I presume that brachycephaly can be induced by direct extrinsic pressure at least until the soft infant's head gets hard.