The idea is from the fiction novel, Romance of Three Kingdoms, which is based off the historical event of Ancient China during The Three Kingdoms Period. The story depicts the events near the end of the Han Dynasty in which warlords rise and fall in attempt to seize control of the land. Some important figures during the era were Sun Jian, Liu Bei, and Cao Cao. These three warlords in practical are the founders of their kingdoms: Sun Jian of Wu, Liu Bei of Shu, and Cao Cao of Wei. These three kingdoms seized dominance over the land of China until only three lords remain which began the Three Kingdoms Era. In the era, these three warlords along with their warriors would fight each other over control to unify China under their rule. If many people aren't familiar with the actual events, I'm sure though that people have heard of the pop culture based off the historical events such as the Dynasty Warriors game series.
I believe this is a good series for LEGOs because it's full of actions and heroic characters. It's like Star Wars and DC universe LEGOS except it's based off the fictional version of historical events. The series also provide a lot of events and plot lines, such as the Yellow Turban Rebellion, Campaign Against Dong Zhuo, and Battle of Chibi and many more. I don't how it might turn out, but I think it's a good idea to consider.
Battle of Hulao Gate: In the novel, the three sworn brothers, Liu Bei, Guan Yu, and Zhang Fei, fought the mighty Lu Bu, who was supposedly the greatest warrior of their time.
Far Left: Liu Bei
Middle: Lu Bu (and Red Hare)
Upper left: Zhang Fei
Right: Guan Yu
Liu Bei, Guan Yu, and Zhang Fei in the novel are sworn brothers by oath they made in a peach garden. The event was called the Oath of the Peach Garden.