She（社）is the God of the Earth, and ji（稷millet）represents the God of the Five Grains. Chinese kings and vassals of ancient times offered sacrifices to these gods. As the Han Chinese depended on farming, these gods were the most important primitive objects of worship. The ancient rulers offered sacrifices to the gods of the Earth and the Five Grains every year to pray for peace and good harvests in the country. As a result, sheji became a symbol of the nation and state power.

Citations

Why do the Sons of Heaven worship the gods of the Earth and the Five Grains? They do so to seek blessings for all under heaven and to requite the gods’ blessings. Without earth, people have nowhere to live; without grain, people have nothing to eat. The earth is too vast to be worshipped everywhere; the variety of grains is too large to be worshipped one by one. Therefore, earth altars to the God of the Earth have been set up to honor the earth; and as millet is the chief one of the five grains, it has become the God of the Five Grains and sacrifices have been instituted. (Debates of the White tiger Hall)