So-called tribute students (gongsheng 貢生) were students selected from among the provincial government students (shengyuan 生員) and given the privilege of a "scholarship" in either the National University (taixue 太學) or the Directorate of Education (guozijian 國子監) directly.
Tribute students would have to pass the lowest level of the state examinations, the provincial examinations (xiangshi 鄉試). The meaning of the expression gongsheng is that these students were given by the provincial administration as "tributes" to the emperor. These "tributes" were brought annually, or every three years, depending on the need.
During the Ming period 明 (1368-1644) there was a range of four different classes of tribute students, namely (regular) annual tribute students (suigong 歲貢, sui gongsheng 歲貢生), (especially) selected students (xuangong 選貢, xuan gongsheng 選貢生), tribute students by imperial grace (engong 恩貢, en gongsheng 恩貢生) and tribute students having paid contributions to obtain the privilege (nagong 納貢, na gongsheng 納貢生).
The Qing dynasty 清 (1644-1911) made use of the classes annual tribute students (suigong), tribute students of excellence (yougong 優貢, you gongsheng 優貢生), tribute students by imperial grace (engong), tribute students for preeminence (bagong 拔貢, ba gongsheng 拔貢生, selected by the court), second-rank tribute students (fugong 副貢, fu gongsheng 副貢生, selected from among the provincial graduates on the "addenda list" fubang 副榜), and "precedent students" (ligong 例貢, li gongsheng 例貢生, because the purchase of the privilege of tribute student followed strict precedent regulations).
The latter class corresponded to the Ming-period nagong class. Depending on the sum paid, such "purchased privileges" corresponded to the examination ranks of excess-quota tribute student (zenggong 增貢, zeng gongsheng 增貢生), additional tribute students (fugong 附貢, fu gongsheng 附貢生), or "salaried tribute student" (lingong 廩貢, lin gongsheng 廩貢生). Usually, these privileges were purchased by government students not having obtained the regular qualification (zige 資格) of "tribute students". Fusheng having bought the title of tribute students were thus called fugong, and so on.
Having left their school in the prefectures, tribute students were called "having left as tribute students" (chugong 出貢).