Kinship, customs, and attitudes related to family life, and strong attachments to community and language were strong influences in the preservation of ethnic identity through the many centuries of foreign domination. The Albanians are divided into two major subgroups--the Gegs, who occupy the area north of the Shkumbin River, and the Tosks, who inhabit the territory to the south. Differences in physical appearance persist, but the breakup of clans and moves toward collectivization of society after World War II diminished the most distinguishing feature, their social system. Antiquated customs and blood feuds that were frequently initiated by offenses against women were more prevalent among the Gegs than the Tosks before the Communist takeover (see ch. 4, The People). The family continued to be a strong social force in 1970. It was the primary residuary of customs, practices, and attitudes that detracted from Communist programs to create a monolithic and modernized society. Older persons, particularly males, who traditionally held positions of authority in the family, were considered to be the strongest force against change. In their efforts to eliminate outmoded customs, Party and government leaders placed special emphasis on youth and women, the latter having suffered much discrimination under the clan system. Large extended families, which sometimes numbered sixty or more persons and included several generations, were in most cases broken up under Communist rule as a means to decrease family influence (see ch. 5, Social System). Party leaders, realizing the importance of education in developing attitudes and loyalties favorable to communism and in training the work force required for a modern industrial economy, placed heavy emphasis on school programs. By 1970 the level of schooling completed by the people had been significantly increased over the 1946 level, but the pool of scientific and skilled personnel fell far short of requirements (see ch. 5, Social System). The most noteworthy improvement in the people's welfare, as reflected by Albanian data, was in the area of health. The incidence of disease was greatly reduced; the death rate decreased; and life expectancy increased by approximately 12.5 years between 1950 and 1966 (see ch. 4, The People). Albanian art, literature, and music have gained little recognition among world cultures. After 1944 the Communist regime instituted mass participation in education and social and cultural activities to instill ideals of socialism and Communist morality and gain the capabilities required for modernization of the economy. Illiteracy, once prevalent among all age groups, was reportedly eliminated among persons under the age of forty and some, but not nearly all, of the skilled work force required has been produced. Despite these efforts Albania's cultural heritage was still meager in the late 1960s (see ch. 5, Social System; ch. 7, Communications and Cultural Development).