In the Song dynasty (960–1279) the imperial examinations became the primary method of recruitment for official posts. More than a hundred palace examinations were held during the dynasty, resulting in a greater number of "jinshi" degrees rewarded. The examinations were opened to adult Chinese males, with some restrictions, including even individuals from the occupied northern territories of the Liao and Jin dynasties. Many individuals of low social status were able to rise to political prominence through success in the imperial examination. Prominent officials who went through the imperial examinations include Wang Anshi, who proposed reforms to make the exams more practical, and Zhu Xi, whose interpretations of the Four Classics became the orthodox Neo-Confucianism which dominated later dynasties. Two other prominent successful entries into politics through the examination system were Su Shi and his brother Su Zhe: both of whom became political opponents of Wang Anshi. The process of studying for the examination tended to be time-consuming and costly, requiring time to spare and tutors. Most of the candidates came from the numerically small but relatively wealthy land-owning scholar-official class.