Yi is one of the constituent states of the Earth Kingdom. Though the state is mountainous and rural, it has significant mineral wealth. After the death of Earth Queen Hou-Ting and the kingdom's descent into chaos, Yi fell prey to roaming bandits who terrorized the local population and caused severe damage, eventually forcing its governor to pledge his allegiance to Kuvira in return for protection from the bandits.
After the kingdom's descent into chaos, the state of Yi fell under siege of hundreds of bandits, leaving it in a critical situation. With its supplies cut off, the governor contacted Tenzin to receive help from the Air Nation.
In 174 AG, Opal and Kai arrived in the governor's city and drove off three bandits. He was pleased to see them, though inquired where the rest of the airbenders were. He was shocked to learn that the two teenagers were all Tenzin was able to send as there were hundreds of more bandits threatening to cause Yi to collapse.
Not long after, Kuvira arrived in Yi with her army, prompting the governor to ask what she was doing there. At her request, he went aboard her train to have a private conversation. Despite the imminent risk of collapse, the governor refused to sign Kuvira's offer, in which she would receive access to all of Yi's resources, namely its rich ore supply, in return for complete protection. He ordered her to leave his state and angrily left the train after being intimidated by the army commander.
After Opal and Kai unsuccessfully attempted to gather supplies from the villages surrounding Yi's capital via the sky, the governor realized that his situation was hopeless and that signing Kuvira's contract was the only way he could protect his citizens. The two airbenders delivered the contract to Kuvira, who returned shortly after to the capital with crates of food and several mecha suits. While her soldiers distributed the supplies, Kuvira declared the state of Yi under her army's protection and forced the governor to pledge his allegiance to her per their agreement if he wanted to retain his position as administrator.