不得要领 — “Unable to grasp the main point or essence”

When Emperor Wu of Han first ascended the throne, defectors from the northern Xiongnu reported that the Xiongnu had defeated the Yuezhi people, turning the Yuezhi king's skull into a drinking cup. The displaced Yuezhi harbored intense hatred towards the Xiongnu and wished to attack them, but lacked assistance from other states. At the time, Emperor Wu himself sought to eliminate the Xiongnu. Hearing this, he desired to establish friendly relations with the Yuezhi. However, reaching the Yuezhi required passing through Xiongnu territory. Thus, he sought volunteers to undertake the mission. Zhang Qian, who had recently become a Lang official, responded to the call and was approved by Emperor Wu.

Unfortunately, during his journey through Xiongnu lands, Zhang Qian was captured and escorted to the Chanyu (Xiongnu leader). The Chanyu detained Zhang Qian and remarked, "The Yuezhi are to our northwest. How can you Han people send envoys there? If we wished to send an envoy to the state of Yue, would you allow us?" Zhang Qian was consequently held captive by the Xiongnu for over ten years. The Xiongnu gave him a wife, and he had a son, but Zhang Qian meticulously preserved the imperial staff entrusted to him by the Han court throughout his captivity.

Later, the Xiongnu relaxed their surveillance. Zhang Qian, along with his attendants, seized the opportunity to escape and headed towards the Yuezhi. After traveling for dozens of days, they reached the state of Dayuan. The King of Dayuan had heard of the Han Empire's wealth and wished to establish relations but had not succeeded. Upon meeting Zhang Qian, he was delighted and asked about his destination. Zhang Qian replied, "I was dispatched by the Han to visit the Yuezhi, but my path was blocked by the Xiongnu. Now, having escaped from them, I hope Your Majesty can provide guides to assist me in reaching the Yuezhi. If I succeed, upon my return to Han, the Han will bestow countless treasures upon your state." The King of Dayuan agreed, sending guides and interpreters who escorted him to Kangju. Kangju, in turn, sent him to the Yuezhi.

It turned out that the Yuezhi, after their king was killed by the Xiongnu, had mostly migrated west and settled in what was now called Dayuezhi. They had installed the slain king's crown prince as their new king, ruling over the previously existing Daxia territory. The land there was fertile, rich in resources, and free from external invasions. They desired only peace and contentment, feeling that the Han was too distant to provide practical assistance, and no longer harbored a strong desire for revenge against the Xiongnu.

Zhang Qian traveled from Dayuezhi to Daxia, yet he could never obtain a clear stance from the Yuezhi regarding an alliance with Han to attack the Xiongnu. They were content with their new peaceful life and had lost their strong desire for revenge. Despite his efforts, Zhang Qian was 'unable to grasp the main point' or 'get a clear commitment' from the Yuezhi, ultimately failing to achieve the primary goal of his mission, which was to form an alliance. After staying there for over a year, he set off on his journey back to Han.