Xu Kingdom!
It was originally a powerful country, but because the current Emperor, Su Guangming, was incompetent and unqualified, it caused the treacherous officials to take over and the loyal officials in the imperial court to be run over.
When fighting with the surrounding Yan Kingdom, they used incompetent generals to take command, resulting in 800,000 soldiers being killed and the kingdom's strength considerably declining. Su Guangming made the Ninth Princess, Su Wan, marry the Yan Emperor and cut off some land, hoping to avoid the calamity of the country's fall.
Who knew that Su Wan had disappeared halfway through the journey. When the Yan Kingdom's Emperor heard about it, he was greatly enraged and ordered the Xu Kingdom Emperor, Su Guangming, to submit to him. Otherwise, he would attack the capital of Xu Kingdom.