That was quite an interesting choice for a challenge. I certainly learned quite a bit from my research, but it was pretty tough because of those darn Qin burning everything! Here is my finished product, the Zhao state.
The civ is based on King Wuling's reforms that greatly increased Zhao's power and influence. Most notably, he made his cavalry wear trousers! At the time, it was considered barbaric and blasphemous to wear "barbarian clothes" during war (especially for the commanders), but Wuling made his armies adopt the war clothing of their northern neighbors and as a result they became much more effective. "Hufu" literally means "clothes of the Hu", which were one of the barbarian tribes closest to Zhao. Their Ji She also learnt horseback archery which was used in combination with cavalry charges.
Zhao (Wuling)
UA: Hufu Reforms - Clearing Barbarian encampments generatesscience towards military technologies. Units that clear encampments may gain a promotion that varies depending on the terrain of the encampment (ex. Flat Tiles give Shock to melee units, Hills give Drill, etc.)
UB: Běi qiáng - Replaces walls. Barbarians within 4 tiles of the city with a běi qiáng are automatically dealt minor damage and loose 1movement point.
UU: Ji She - Zhao replacement for the Horseman with a 33% combat bonus against barbarians. Has the ability to perform eitherranged attacks or melee attacks, but cannot do both in the same turn. Gains the Formation promotion upon clearing an encampment.
The civ is based on King Wuling's reforms that greatly increased Zhao's power and influence. Most notably, he made his cavalry wear trousers! At the time, it was considered barbaric and blasphemous to wear "barbarian clothes" during war (especially for the commanders), but Wuling made his armies adopt the war clothing of their northern neighbors and as a result they became much more effective. "Hufu" literally means "clothes of the Hu", which were one of the barbarian tribes closest to Zhao. Their Ji She also learnt horseback archery which was used in combination with cavalry charges.
Xianyang
Production when building infantry land units and build twice faster. Can spend 
Gold (cost modified by another civillization's unhappiness) to boost one of your city's growth and decrease adjancent civ's city's growth for several turns, with a chance of diplomatic penalty
Social Policy cost by 1%. +1 
Food in the city per Farm
Legalism points from killing units, creating wonders and finding natural ones as well as from destroying foreign 
great works of writing, which also grants you 
city states.
). A question for Mobfire: on the horse replacement, is the "additional ranged attack" an impi style pre-melee or a camel style unit rehash?
of the base melee attack. I edited my original post to make that more clear.
Happiness in the Capital.
Faith when filled with a 
Great Person is expended.
traded with other civilizations. 
