About 2000 years ago.
An ancient empire in China,漢帝國( Han Empire), was frequently invaded and harassed by 匈奴( Xiongnu), a strong nomadic kingdom in the west of Han Empire.
Many soldiers died in the fire of wars, and more people died under the trample from 匈奴( Xiongnu).
People were enforced to leave form their home to move into the east.
Since Han Empire was built, the emperors of Han Empire always adopted moderate diplomacy to their strong and dreadful harasser.
In order to maintain peace and avoid being harassed, they gave lots of tributes such as gold, pearls, exquisite silks, and even including their daughters; which meant they adopted the policy of marrying daughters of the Imperial family to their enemy for a temporary armistice.
劉徹(Liu Che), the fourth emperor of Han Empire.
He ever lost her loved family.
His sister and daughter were married to his enemy, and his brother died in the battlefield.
The deep hatred in his heart made him strong.
He wanted to build a great army not only to defend his people and empire, but also to annihilate his enemy.
He believed that one day his empire wouldn't just defend but take revenge on its enemy.
He made many reformations including declaiming the Confucianism as the dominated doctrine of Han Empire.
Of course, there were also many anecdotes in Han Empire about love, family, wars, social phenomena, or emperors.
Even 1000 years later, there were still many great Chinese poets wrote majestic poem for praising for the patriotism and the melancholy of this Empire.
劉徹(Liu Che) knew that in order to accomplish his plan he needed an ally, a strong and reliable friend.
And in the meanwhile someone advised him to ally Han with a far west empire.
That empire was called "大月氏".
Actually, in that time, for most Chinese, 大月氏was just more than a legend, none ever really been there, let alone considered "大月氏" as an ally.