As landholders and drafted government officials, the gentry considered themselves the leading members of society; gaining their cooperation and employment was essential for the county or provincial bureaucrat overburdened with official duties. In many ways, scholar-officials of the Song period differed from the more aristocratic scholar-officials of the Tang dynasty (618–907). Civil service examinations became the primary means of appointment to an official post as competitors vying for official degrees dramatically increased. Frequent disagreements amongst ministers of state on ideological and policy issues led to political strife and the rise of political factions. This undermined the marriage strategies of the professional elite, which broke apart as a social group and gave way to a multitude of families which provided sons for civil service.