It was considered a super state 40 years prior to the story line, but was crushed and reduced to a small portion of it by a coalition army led by the 'Military God' Gaku Ki. They lost everything except for the two cities of Sokuboku and Kyo.
This coalition army may have been formed in response to their invasion into Yan territory, which ended in failure as they were defeated by Gaku Ki and Geki Shin.
In 241 BC, the king of Qi was approached by Sai Taku of Qin and withdrew his troops from the coalition army invading Qin. After the coalition army was defeated at Kankoku Pass, it invaded Qi. The cities of Hei and Sou fell almost instantly to the onslaught. The coalition army made it as far as the city of Jouan, before it was driven off.
The state is a monarchy and is ruled by King Ou Ken. He is an old friend of Sai Taku, Qin's official of diplomacy.
During the time as a super state, the Qi military was considered very powerful as it almost bought Yan to the brink of destruction. The Qi military is organized from top to bottom by; Great Generals, Generals, 1000-man commanders, 300-man commanders, 100-man commanders and finally Go's (five man units).