In the past the clan leader of Gu Clan swore a blood oath with Xiao Xuan to not invade each others clans.
They are known as one of the strongest ancient clans alongside the Hun clan. Gu(古) means old or ancient in Chinese.
Most of Gu Clan is located in the Gu Realm which is located in the Center East Region of the Center Continent of the Dou Qi continent. More specifically, the portal that leads to Gu Realm is located there.
They have multiple Dou Zuns,Ban Shengs and Dou Shengs within their ranks. They have their own army called Black Submerged Army, which is rumored to be where the strongest warriors of the Gu clan gathered. There are Eight Great Commanders, Four Great Generals and Two leaders forming Black Submerged Dukes. This Clan possesses their own flying warships too.
Gu Clan holds Ceremony where are their young generations get their Clan Tattoo according to the Purity of the Dou Di Bloodline. Strictly Speaking only those above Grade 4 are tested for this. The clan tattoo is divided into four levels: silver, gold, purple-gold and rainbow-gold. Rainbow Gold is only Given to people with Grade 10(Divine) Dou Di Bloodline. Within the past 1000 years, it seems that only Xiao Xun-er possess the perfect pure Dou Di bloodline in the entire Gu Clan .
Their 3 stronger fighters aside from their clan leader are called the 3 Immortals of the Gu Clan who are at least 6 star Dou Sheng or higher.